Ontario Structure Inspection Manual (OSIM)

Transcription

Ontario Structure
Inspection Manual
(OSIM)
Ministry
of
Transportation
POLICY, PLANNING & STANDARDS DIVISION
ENGINEERING STANDARDS BRANCH
BRIDGE OFFICE
October, 2000
(Revised: Nov. 2003, Apr. 2008)
To all users of the:
ONTARIO STRUCTURE INSPECTION MANUAL (OSIM)
Enquiries regarding amendments, suggestions or comments should be directed to:
Bridge Office
Ministry Of Transportation
2nd Floor
301 St. Paul Street
St. Catharines, Ontario
L2R 7R4
(905) 704-2406
ISBN 0-7794-0431-9
© The Queen's Printer for Ontario
Reproduced with permission
Although the contents of this manual have been checked no warranty, expressed or implied, is made by the
Ministry of Transportation as to the accuracy of the contents of this manual, nor shall the fact of distribution
constitute any such warranty, and no responsibility is assumed by the Ministry of Transportation in any
connection therewith. It is the responsibility of the user to verify its currency and appropriateness for the use
intended, to obtain the revisions, and to disregard obsolete or inapplicable information.
OSIM
CONTENTS
PREFACE
INTRODUCTION
GENERAL DEFINITIONS
PART 1 - TECHNICAL INFORMATION
PART 2 - DETAILED VISUAL INSPECTIONS
PART 3 - ADDITIONAL INVESTIGATIONS
PART 4 - MATERIAL CONDITION SURVEYS
PART 5 - UNDERWATER INSPECTIONS
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Oct. 2000
PREFACE
The Ontario Structure Inspection Manual has been used for bridge inspections in Ontario since 1985.
The manual underwent significant modifications in the year 2000. The Manual will continue to evolve
and comments and suggestions will be recorded and, if necessary, revisions will be made.
A new “severity and extent” philosophy has been adopted in order to simplify the process of using
inspection information to estimate bridge rehabilitation needs and costs. The inspection process is quite
similar to the old process except for changes in the way that inspection data is recorded. Material
defects of various bridge components, as defined in Section 2, Part 1 of this manual are still valid. The
new approach requires that more quantitative data be collected and recorded on the Condition State of
bridge elements. Part 1 of the manual also describes the various components of a bridge. These
components are grouped into convenient “Elements” for inspection purposes as described in Part 2.
Although, primary, secondary and auxiliary components are described in Part 1, for inspection
purposes, no distinction is made between these types of components.
The previous Material Condition Rating Tables in Part 2 of the manual have been replaced with
Condition State Tables. Four Condition States have been defined for bridge elements, namely,
Excellent, Good, Fair and Poor. The condition of bridge elements is defined to be in any one or more of
these Condition States. At any given time, areas within a bridge element may be in different Condition
States, or the whole of the element may be in the same Condition State. For each bridge element, the
inspector assesses and records the amount (area, length or unit as appropriate) of the element in each of
the four Condition States. This assessment is based predominately on visual observations, however,
some non-destructive testing, such as hammer tapping of concrete for delamination, will be required to
determine or verify areas in poor condition. Where an area in poor condition is noted, the area is to be
delineated and measured.
The previous Performance Condition Rating Tables in Part 2 have been deleted. The new inspection
method requires suspected Performance Deficiencies to be identified for each bridge element.
Performance deficiencies are chosen from a standard list and are used to flag areas that require the
inspector to take some follow-up action subsequent to the inspection. The inspector should also
identify maintenance needs. A standard list of maintenance needs has been created.
Modifications to the manual include:
Part 1 - Technical Information (Section 1 has been completely re-written)
- Ministry of Transportation procedural guidelines have been deleted in an
effort to make the manual more generic
- Minor wording changes have been made to the description of some of the
material defects in Section 2
Part 2 - Detailed Visual Inspections (This Part has been completely re-written)
- Material Condition Rating (MCR)Tables have been deleted and Condition
State Tables have been added
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Apr. 2008
Oct. 2000
-
Performance Condition Rating (PCR) Tables have been deleted and a
Suspected Performance Deficiency Tables have been added
Element lists have been added for each bridge type
Quantity calculation tables have been added
Maintenance Needs Tables have been added
Old inspection forms have been deleted and new forms have been added
Photograph descriptions have changed to reflect Condition State language
Part 3 - Additional Investigations (This Part has been completely re-written)
- Reference to load posting has been deleted and covered in Suspected
Performance Deficiency Section
- Wording changes have been made for condition surveys and other
investigations
Part 4 - Material Condition Surveys
- No change
Part 5 - Underwater Inspections
- No change
November 2003 Revisions
These 2003 minor revisions are indicated with a single revision bar in the margin. The main purpose of
these revisions was:
• to clarify the level of detail required during the inspection,
• to redefine Asphalt defects in term of top-down and bottom-up defects,
• to clarify the Condition State Table for inspection of asphalt covered concrete decks,
• to clarify the recommended work and add a 6 to 10 year timeframe for recommended
work,
• to address other minor clarifications.
April 2008 Revisions
These 2008 revisions are indicated with a double revision bar in the margin. The main purpose of these
minor revisions was:
• to clarify the definition of biennial inspection and of culverts,
• to revise wood defects and defects related to soil steel structures,
• to change the units of measure for some bridge elements and to add some elements as
optional.
• To change the way recommended work is recorded for elements and for the overall
structure.
• to address other minor clarifications.
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Oct. 2000
INTRODUCTION
The need for mobility requires that Ontario's highway system be kept in good repair.
Structures are a vital part of this system. The efficiency of the system is impaired and the
public inconvenienced if a structure fails or its load-carrying capacity is reduced for any
reason. To avoid such failings, an effective structure management system is required.
An essential component of structure management system involves the systematic inspection
of the structures on the highway network.
This manual sets standards for detailed visual inspection and condition rating of structures
and their components. It provides a uniform inspection approach for all structures in Ontario.
Part 1 gives general details of inspection procedures, bridge components, material defects
and performance defects
Part 2 sets out requirements for detailed visual inspection and condition rating of structures
and their components.
Part 3 provides guidelines for the need to carry out further investigations and special studies.
Part 4 describes various types of procedures and equipment for the non-destructive testing of
materials and provides guidelines and requirements for carrying out these tests.
Part 5 provides guidelines and requirements for underwater investigations.
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Oct. 2000
GENERAL DEFINITIONS
Abutment
- A substructure unit which supports the end of the structure and retains
the approach fill.
Auxiliary
Components
- Any component which does not share in the load carrying
capacity of the structure.
Biennial
Structure
Inspection
An inspection performed in every second calendar year to assess the
condition of the structure, in accordance with the methodology described
in OSIM.
Bridge
- A structure which provides a roadway or walkway for the passage of
vehicles, pedestrians or cyclists across an obstruction, gap or facility and
is greater than or equal to 3 m in span.
Chord
- The upper and lower main longitudinal component in trusses or
arches extending the full length of the structure.
Coating
- The generic term for paint, lacquer, enamel, sealers, galvanizing,
metallizing, etc.
Concrete Deck - A detailed inspection of a concrete deck in accordance with The Structure
Rehabilitation Manual.
Condition
Survey
Culvert
(Structural)
- A Structure that forms an opening through soil and;
a) Has a span of 3 metres or more (e.g. S in the diagrams below), or
S
S
S
i – Soil Steel (Any Shape)
ii – Soil Steel Arch
S
S
iv – Concrete Box
v – Timber
iii – Concrete Barrel Arch
S
vi – Concrete Open Footing
b) Has the sum of the individual spans of 3 metres or more, for
adjacent multiple cell culverts (e.g. a+b+c in the diagrams below),or
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Apr. 2008
a
b
c
a
b
c
i – Concrete Box
ii – Timber
a
b
c
iii – Concrete Open Footing
c) Has the sum of the individual spans of 3 metres or more, for
multiple cell culverts (each with spans at least 2m) separated by
soil (a width not more than the span of smallest individual cell) (e.g.
a+b+c in the diagrams below, where a, b, and c are all ≥ 2.0m and
d and e are both ≤ the minimum of a, b, and c), or
a
b
d
a
c
d
b
e
c
e
ii – Multi-Cell Concrete Box
i – Multi-Cell Soil Steel
a
d
b
e
c
iii – Multi-Cell Concrete Open Footing
a
d
b
e
c
iv – Multi-Cell Timber
d) Has been designated by the Owner as qualifying as a culvert.
Defect
- An identifiable, unwanted condition that was not part of the original intent
of design.
Detailed
Visual
Inspection
- An element by element visual assessment of material defects,
performance deficiencies and maintenance needs of a structure.
Deterioration
- A defect that has occurred over a period of time.
Diagonals
- Component which spans between the top and bottom chord of a truss or
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Apr. 2008
arch in a diagonal direction.
Distress
- A defect produced by loading.
Elements
- The individual parts of a structure defined for inspection purposes.
Several bridge components may be grouped together to form one bridge
element for inspection purposes
Engineer
- A member or licensee of the Professional Engineers of Ontario.
Environment
- An element’s exposure to salt spray:
Benign - Not exposed (e.g. River Pier)
Moderate - Exposed but element protected
(e.g. Asphalt covered and waterproofed deck)
Severe - Exposed and element not protected
(e.g. Exposed concrete deck, Barrier Wall)
Evaluation
- The determination of the load carrying capacity of structures in
accordance with the requirements of the Canadian Highway Bridge
Design Code.
Floor Beam
- Transverse beams that span between trusses, arches or girders and
transmit loads from the deck and stringers to the trusses, arches or
girders.
Highway
- A common and public thoroughfare including street, avenue, parkway,
driveway, square, place, bridge, designed and intended for, or used by,
the general public for passage of vehicles, pedestrians or animals.
Lateral
Bracing
- Bracing which lies in the plane of the top or bottom chords or flanges and
provides lateral stability and resistance to wind loads.
Maintenance
- Any action which is aimed at preventing the development of defects or
preventing deterioration of a structure or its components.
Masonry
- Structure made up of natural stones separated by mortar joints, usually in
uniform courses. Masonry in existing structures is usually in retaining
walls, abutments, piers or arches.
Masonry
Ashlar
- Stone worked to a square shape or cut square with uniform coursing
height and vertical joints staggered. The stone has a minimum course
height of 200 mm set in joints with an average thickness of 10 mm or less.
Masonry
Squared
Stone
- Stone in natural bed thicknesses or roughly squared stones with course
height less than 200 mm and joints greater than 10 mm but not over 20
mm.
Masonry
Rubble
- Stone masonry constructed with rough field stones or only roughly
squared stones set in mortar joints with average thickness greater than
20 mm. Also any squared stone masonry in which the joints are greater
than 20 mm, but less than 30 mm in thickness.
Minister
- The Minister of the Ministry of Transportation of Ontario or his nominee.
Ministry
- The Ministry of Transportation of Ontario
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Apr. 2008
Owner
- A person having jurisdiction and control over the structure.
Person
- An individual, board, commission, partnership or corporation, including a
municipal corporation, and employees, agents, successors and assigns of
any of them.
Plans
- All drawings, descriptions and specifications, being parts of the contract,
and all drawings and descriptions produced by the constructor for the
erection of a bridge or structure, and all revisions thereto.
Portal Bracing
- Overhead bracing at the ends of a through truss or arch and provides
lateral stability and shear transfer between trusses.
Primary
Components
- The main load carrying components of the structure.
Rehabilitation
- Any modification, alteration, retrofitting or improvement to a structure subsystem or to the structure which is aimed at correcting existing defects or
deficiencies.
Repair
- Any modification, alteration, retrofitting or improvement to a component of
the structure which is aimed at correcting existing defects or deficiencies.
Retaining Wall
- Any structure that holds back fill and is not connected to a bridge.
Secondary
Components
- Any component which helps to distribute loads to primary components, or
carries wind loads, or stabilizes primary components.
Sign Support
- A metal, concrete or timber structure, including supporting brackets,
service walks and mechanical devices where present, which support a
luminaire, sign or traffic signal and which span or extend over a highway.
Span
- The horizontal distance between adjacent supports of the superstructure
of a bridge, or the longest horizontal dimension of the cross-section of a
culvert or tunnel taken perpendicular to the walls.
Stringers
- Stringers span between floor beams and provide the support for the deck
above.
Structure
- Bridge, culvert, tunnel, retaining wall or sign support.
Suspected
Performance
Deficiency
- A Suspected Performance Deficiency should be recorded during an
inspection, if an element’s ability to perform its intended function is in
question, and one or more performance defects exist.
Sway Bracing
- Vertical bracing spanning between through trusses or arches, or outside
of half-through trusses or arches and providing lateral stability and shear
transfer between the trusses or arches.
Tunnel
- Any bridge that is constructed through existing ground, and is used to
convey highway or railway traffic through it.
Verticals
- Components which span between the top and bottom chords of a truss
or arch in the vertical direction.
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Apr. 2008
Part 1 – Technical Information
PART 1 - TECHNICAL INFORMATION
CONTENTS
SECTION 1
STRUCTURAL INSPECTIONS .................................................................................. 1-1-1
SECTION 2
MATERIAL DEFECTS ................................................................................................ 1-2-1
SECTION 3
STREAMS AND WATERWAYS ................................................................................ 1-3-1
SECTION 4
EMBANKMENTS AND SLOPE PROTECTIONS ..................................................... 1-4-1
SECTION 5
SUBSTRUCTURES ...................................................................................................... 1-5-1
SECTION 6
BEARINGS ................................................................................................................... 1-6-1
SECTION 7
JOINTS .......................................................................................................................... 1-7-1
SECTION 8
SUPERSTRUCTURES .................................................................................................. 1-8-1
SECTION 9
DECK COMPONENTS ................................................................................................ 1-9-1
SECTION 10 BARRIERS .................................................................................................................... 1-10-1
SECTION 11 STRUCTURAL STEEL COATINGS .......................................................................... 1-11-1
SECTION 12 SIGNS ........................................................................................................................... 1-12-1
SECTION 13 ATTACHMENTS ......................................................................................................... 1-13-1
SECTION 14 LIVE LOADS ................................................................................................................ 1-14-1
Apr. 2008
1-i
Oct. 2000
SECTION 1 - STRUCTURAL INSPECTIONS
Contents
1.1
Structural Inspections
1.2
Goal and Objectives of Structural Inspections ......................................................................... 1-1-2
1.2.1 Goal .............................................................................................................................. 1-1-2
1.2.2 Objectives ..................................................................................................................... 1-1-2
1.3
Inspections of Structures ......................................................................................................... 1-1-2
1.3.1 Frequency of Detailed Visual Inspections ................................................................. 1-1-2
1.3.2 Enhanced OSIM Inspections ...................................................................................... 1-1-3
1.3.3 Emergency Inspections ............................................................................................. 1-1-4
1.3.4 Additional Investigations ......................................................................................... 1-1-4
1-1-1
Apr. 2008
1.1 STRUCTURAL INSPECTIONS
This section sets out the goals and objectives of structural inspections. It identifies the types of inspections and
the types of structures to which this manual applies.
1.2 GOAL AND OBJECTIVES OF STRUCTURAL INSPECTIONS
1.2.1 Goal
The goal of structural inspections is to ensure, within an economic framework, an acceptable standard for
structures in terms of public safety, comfort and convenience.
1.2.2 Objectives
The main objectives of Structural Inspections are:
•
•
•
•
to maintain structures in a safe condition;
to protect and prolong the useful life of structures;
to identify maintenance, repair and rehabilitation needs of structures; and,
to provide a basis for a structure management system for the planning and funding of the maintenance and
rehabilitation of structures.
1.3 INSPECTIONS OF STRUCTURES
To achieve the goal and objectives of structural inspections, detailed visual inspections of bridges should be
performed regularly. A detailed visual inspection is an element-by-element “close-up” visual assessment of
material defects, performance deficiencies and maintenance needs of a structure. “Close-up is defined as “a
distance close enough to determine the condition of the element”. In many cases, the inspection should be
conducted within arms length of the element, possibly involving tapping with a hammer or making
measurements by hand. In some cases (provided that periodic Enhanced OSIM inspections are done as
described in Section 1.3.2), it may be possible to inspect a portion of the bridge close-up and then
estimating the condition of the remaining inaccessible parts by visually comparing them to the partial
close-up inspection. It is expected that in order to adequately assess the condition of all elements, the
inspector should plan to spend at least 2 to 3 hours at a typical bridge site. For large bridges, this time
will increase.
Appropriate special equipment (Bridgemaster, bucket truck, ladders, etc) should be used to facilitate this
assessment.
In addition to detailed inspections, routine inspections by maintenance crews are essential, and should be
performed regularly to identify sudden changes in bridge condition. This manual describes the procedures for
carrying out detailed visual inspections only.
1.3.1 Frequency of Detailed Visual Inspections
The following structures shall be inspected every two years (Biennially):
•
•
•
All bridges, culverts and tunnels with spans of 3 metres or greater
All retaining walls
All movable bridges
1-1-2
Apr. 2008
For culverts with 3 to 6 metre spans and retaining walls, the inspection interval can be increased to four years if
the culvert or retaining wall is in good condition and the engineer believes that the culvert or retaining wall
condition will not change significantly before the next inspection.
The timeframe of two years (and four years) refers to calendar years and the inspection need not be done before
the second (or fourth) anniversary of the previous inspection.
It is recognized that the level of effort involved in performing a detailed visual inspection will vary depending on
structure type and age. For example, if a bridge is less than 5 years old, it is unlikely that there will be much
change in bridge condition from one inspection to the next. Consequently, the inspection time may be relatively
short. However, the inspector must be satisfied that everything possible has been done to determine the
condition of the various bridge elements.
It is also recognized that one of the purposes of regular inspections is to identify changes in bridge condition. If
taken in this context, the importance of having a qualified inspector assess the condition of structure every two
years, cannot be over emphasized.
The frequency of inspections given above, applies to all structures in good repair. The maximum inspection
interval and the level of inspection may however vary for certain structures. Some structures may have to be
inspected more frequently as directed by the Engineer. Such action can be justified based upon the type of
structure, construction details, existing problems or restrictions, and material and performance condition history.
Structures or components requiring more frequent inspection include:
•
•
•
•
•
•
•
•
•
structures with a high proportion of elements in the Poor Condition State;
structures with load limits on them;
new types of structures or details with no previous performance history;
structures with load or clearance restrictions;
single load path structures;
structures with fatigue prone details;
structures with fracture critical components;
pins and hangers in arch structures;
pins in suspended spans and pinned arches.
Often, more detailed investigations and non-destructive testing techniques are required to identify defects
for the above cases. The inspector should recommend that these specialized additional investigations be
performed regularly, where warranted, as described in Part 3 of this Manual.
Inspection procedures detailed in this manual do not apply to the mechanical or electrical parts of movable
bridges. The inspection of overhead sign support structures (not roadside signs) is covered in the Ontario Sign
Support Inspection Guidelines. Bridge mounted sign supports and hardware should also be inspected in
accordance with the Ontario Sign Support Inspection Guidelines. For ease of access, the inspector should plan
to inspect these components when on site for the biennial bridge inspection.
1.3.2
Enhanced OSIM Inspections
For a typical OSIM inspection, on structures that are in generally good condition, it may be possible to inspect a
portion of the bridge close-up and then estimate the condition of the remaining inaccessible parts by visually
comparing them to the partial close-up inspection. Periodically, the structure should be inspected more
thoroughly by actually getting within arms reach of all areas of the structure. This often requires special
equipment and tools to be able to access all areas of the structure. This Enhanced OSIM inspection should
1-1-3
Apr. 2008
typically be done for structures that are over 30 years old with critical components in Poor condition. The
frequency of the Enhanced OSIM inspection should be a maximum of six years. The additional effort required
for an Enhanced OSIM inspection includes the following:
- Tapping all areas of concrete with a hammer to determine limits of delamination and spalling.
- Tapping all areas of wood with a hammer to determine limits of rot, as well as selective wood coring to
correlate tapping with the presence of inner rot or other damage.
- Cleaning and wire brushing all areas of steel, including connections to ascertain section loss.
1.3.3
Emergency Inspections
An emergency situation exists when a structural component contributing to overall stability of the structure has
failed, or is in imminent danger of failure or public safety is in any way at risk. In such cases, a detailed visual
inspection should be carried out immediately. Typical problems that may cause an emergency situation to
develop are:
• Accident or vehicle collision with a structure;
• Spring run-off or major flooding;
• An earthquake;
• Cracks in steel components; and
• Loose concrete in an overhead structure.
1.3.4
Additional Investigations
If during a detailed visual inspection, the inspector feels that more detailed information is needed, additional
investigations can be requested. Some of these investigations are:
• Detailed Deck Condition Survey;
• Non-destructive Delamination Survey of Asphalt Covered Decks;
• Concrete Substructure Condition Survey;
• Detailed Coating Condition Survey;
• Detailed Timber Investigation;
• Post-Tensioned Strand Investigation;
• Underwater investigation;
• Fatigue investigation;
• Seismic investigation; or
• Structure evaluation.
Information on these inspections is contained in Part 3 of this manual.
1-1-4
Apr. 2008
SECTION 2
-
MATERIAL DEFECTS
Contents
2.1
Material Defects
............................................
1-2-2
2.2
Concrete ....................................................
2.2.1
Scaling .............................................
2.2.2
Disintegration ......................................
2.2.3
Erosion .............................................
2.2.4
Corrosion of Reinforcement ..........................
2.2.5
Delamination ........................................
2.2.6
Spalling ............................................
2.2.7
Cracking ............................................
2.2.8
Alkali Aggregate Reaction ...........................
2.2.9
Surface Defects .....................................
1-2-2
1-2-3
1-2-3
1-2-4
1-2-4
1-2-5
1-2-5
1-2-6
1-2-7
1-2-8
2.3
Steel
2.3.1
2.3.2
2.3.3
2.3.4
2.4
Wood ........................................................ 1-2-25
2.4.1
Checks, Splits and Shakes ........................... 1-2-25
2.4.2
Weathering .......................................... 1-2-25
2.4.3
Rot or Decay ........................................ 1-2-26
2.4.4
Insect Damage ....................................... 1-2-27
2.4.5
Abrasion and Wear ................................... 1-2-27
2.4.6
Cracking, Splintering, Crushing and Shattering ...... 1-2-28
2.4.7
Fire and Chemical Damage ............................ 1-2-28
2.4.8
Connection Deficiencies ............................. 1-2-29
2.5
Masonry .....................................................
2.5.1
Cracking ............................................
2.5.2
Splitting, Spalling and Disintegration ..............
2.5.3
Loss of Mortar and Stones ...........................
1-2-36
1-2-36
1-2-36
1-2-37
2.6
Aluminum ....................................................
2.6.1
Corrosion ...........................................
2.6.2
Cracking ............................................
2.6.3
Connection Deficiencies .............................
1-2-40
1-2-40
1-2-41
1-2-41
.......................................................
Corrosion ...........................................
Permanent Deformations ..............................
Cracking ............................................
Connection Deficiencies .............................
1-2-18
1-2-18
1-2-19
1-2-19
1-2-20
1-2-1
Apr. 2008
2.7
Asphalt
2.7.1
2.7.2
2.7.3
2.7.4
2.7.5
2.7.6
2.7.7
2.7.8
Pavement ............................................
Cracking ............................................
Ravelling ...........................................
Loss of Bond and Delamination .......................
Potholes ............................................
Wheel Track Rutting .................................
Rippling ............................................
Flushing ............................................
Slippery Surface ....................................
1-2-44
1-2-44
1-2-45
1-2-46
1-2-46
1-2-47
1-2-47
1-2-48
1-2-48
2.8
Coatings ....................................................
2.8.1
Coating Related Defects .............................
2.8.2
Adhesion Related Defects ............................
2.8.3
Application Related Defects .........................
1-2-55
1-2-56
1-2-56
1-2-57
2.9
References
2.1
MATERIAL DEFECTS
.................................................. 1-2-66
This section describes the defects that are normally found in concrete, steel,
wood, masonry, aluminum, asphalt pavements and coatings. Each defect is briefly
described and the causes producing it are identified. Severity levels, wherever
possible, are established.
2.2
CONCRETE
Concrete is used in structures as plain concrete, such as in tremie and mass
concrete; or, it is combined with conventional steel reinforcement as reinforced
concrete, or with prestressing steel reinforcement as prestressed concrete.
Defects in concrete can often be related to the lack of durability of the concrete,
resulting from the composition of the concrete, poor placement practices, poor
Quality Control or the aggressive environment in which it is placed.
The following defects commonly occurring in concrete are described:
-
Scaling
Disintegration
Erosion
Corrosion of Reinforcement
Delamination
Spalling
Cracking
Alkali-Aggregate Reaction
Surface Defects
1-2-2
2.2.1
SCALING
Scaling is the local flaking, or loss of the surface portion of concrete or mortar
as a result of the freeze-thaw deterioration of concrete. Scaling is common in non
air-entrained concrete, but can also occur in air-entrained concrete in the fully
saturated condition. Scaling is prone to occur in poorly finished or overworked
concrete where too many fines and not enough entrained air is found near the
surface. Scaling of concrete is shown in Figure 2.2.1.
Severity
Light
- Loss of surface mortar to a depth of up to 5 mm without exposure of
coarse aggregate;
Medium
- Loss of surface mortar to a depth of 6 to 10 mm with exposure of
some coarse aggregates;
Severe
- Loss of surface mortar to a depth of 11 mm to 20 mm with aggregate
particles standing out from the concrete and a few completely lost.
Very
Severe
- Loss of surface mortar and aggregate particles to a depth greater
than 20 mm.
2.2.2
DISINTEGRATION
Disintegration is the physical deterioration or breaking down of the concrete into
small fragments or particles. The deterioration usually starts in the form of
scaling and, if allowed to progress beyond the level of very severe scaling is
considered as disintegration. Disintegration may be caused by de-icing chemicals,
sulphates, chlorides or by frost action.
Disintegration of the concrete is
illustrated in Figure 2.2.2.
Severity
Light
- Loss of section up to 25 mm in depth with some loss of coarse
aggregate;
Medium
- Loss of section between 25 mm and 50 mm deep with considerable loss
of coarse aggregate and exposure of reinforcement;
Severe
- Loss of section between 50 mm and 100 mm deep with substantial loss
of coarse aggregate and exposure of reinforcement over a large area.
Very
Severe
- Loss of section in excess of 100 mm deep and extending over a large
area.
1-2-3
2.2.3
EROSION
Erosion is the deterioration of concrete brought about by water-borne sand and
gravel particles scrubbing against concrete surfaces.
Similar, damage may be
caused by flowing ice. Erosion is sometimes combined with the chemical action of
air and water-borne pollutants which accelerate the breakdown of the concrete.
Erosion is generally an indication that the concrete is not durable enough for the
environment in which it has been placed. Severe erosion of a concrete footing is
shown in Figure 2.2.3.
Severity
Light
- Loss of section up to 25 mm in depth with some loss of coarse
aggregate;
Medium
- Loss of section between 25 mm and 50 mm deep with considerable loss
of coarse aggregate and exposure of reinforcement;
Severe
- Loss of section between 50 mm and 100 mm deep with substantial loss
of coarse aggregate and exposure of reinforcement over a large area.
Very
Severe
- Loss of section is in excess of 100 mm deep and extending over a
large area.
2.2.4
CORROSION OF REINFORCEMENT
Corrosion is the deterioration of reinforcement by electrolysis.
The alkali
content in concrete protects the reinforcement from corrosion.
However, when
chloride ions above a certain concentration are dissolved in water and penetrate
through the concrete to the reinforcement this protection breaks down and corrosion
starts.
In the initial stages, corrosion may appear as a rust-stain on the
concrete surface.
In the advanced stages, the surface concrete above the
reinforcement cracks, delaminates and spalls off exposing heavily rusted
reinforcement. This process is illustrated in Figure 2.2.4(a).
Severity
Light
- Light rust stain on the concrete surface;
Medium
- Exposed reinforcement with uniform light rust.
Loss of reinforcing steel section less than 10%;
Severe
- Exposed reinforcement with heavy rusting and localized pitting.
Loss of reinforcing steel section between 10% and 20%;
Very
Severe
- Exposed reinforcement with very heavy rusting and pitting.
Loss of reinforcing steel section over 20%.
1-2-4
2.2.5
DELAMINATION
Delamination is defined as a discontinuity of the surface concrete which is
substantially separated but not completely detached from concrete below or above
it. Visibly, it may appear as a solid surface but can be identified as a hollow
sound by tapping or chain dragging. Delamination begins with the corrosion of
reinforcement and subsequent cracking of the concrete. However, in the case of
closely spaced bars, the cracking extends in the plane of the reinforcement
parallel to the exterior surface of the concrete. Delamination in a concrete beam
is shown in Figure 2.2.5.
Delamination or debonding may also occur in concrete that has been patched or
overlaid due to the continued deterioration of the older concrete. This may happen
even in the absence of any rusting of reinforcing steel.
Severity
Light
- Delaminated area measuring less than 150 mm in any direction.
Medium
- Delaminated area measuring 150 mm to 300 mm in any direction.
Severe
- Delaminated area measuring 300 mm to 600 mm in any direction.
Very
Severe
- Delaminated area measuring more than 600 mm in any direction.
2.2.6
SPALLING
A spall is a fragment, which has been detached from a larger concrete mass.
Spalling is a continuation of the delamination process whereby the actions of
external loads, pressure exerted by the corrosion of reinforcement or by the
formation of ice in the delaminated area results in the breaking off of the
delaminated concrete.
The spalled area left behind is characterized by sharp
edges. Very severe spalling in a concrete beam and local severe spalling in a
concrete deck are illustrated in Figures 2.2.6(a) and 2.2.6(b) respectively.
Vehicular, ice flow or other impact forces on exposed concrete edges, deck joints
or construction joints, may also result in the spalling or breaking off of pieces
of concrete locally.
Spalling may also be caused by overloading of the concrete in compression. This
results in the breaking off of the concrete cover to the depth of the outer layer
of reinforcement. Spalling may also occur in areas of localized high compressive
load concentrations, such as at structure supports, or at anchorage zones in posttensioned concrete.
Spalling of patched areas may occur due to continued deterioration of the old
concrete and subsequent breaking off of the new patch.
1-2-5
Severity
Light
- Spalled area measuring less than 150 mm in any direction or less
than 25 mm in depth.
Medium
- Spalled area measuring between 150 mm to 300 mm in any direction or
between 25 mm and 50 mm in depth.
Severe
- Spalled area measuring between 300 mm to 600 mm in any direction or
between 50 mm and 100 mm in depth.
Very
Severe
- Spalled area measuring more than 600 mm in any direction or greater
than 100 mm in depth.
2.2.7
CRACKING
A crack is a linear fracture in concrete which extends partly or completely through
the member. Cracks in concrete occur as a result of tensile stresses introduced in
the concrete.
Tensile stresses are initially carried by the concrete and
reinforcement until the level of the tensile stresses exceeds the tensile capacity
(modulus of rupture) of the concrete. After this point the concrete cracks and the
tensile force is transferred completely to the steel reinforcement. The crack
widths and distribution is controlled by the reinforcement in reinforced and
prestressed concrete, whereas in plain concrete there is no such control.
The build-up of tensile stresses and, therefore, cracks in concrete may be due to
externally applied loads, external restraint forces, internal restraint forces,
differential movements and settlements, or corrosion of reinforcement. Externally
applied loads generate a system(s) of internal compressive and tensile stresses, in
the members and components of the structure, as required to maintain static
equilibrium. Cracks resulting from externally applied loads initially appear as
hairline cracks and are harmless. However, as the reinforcement is further stressed
the initial cracks open up and progressively spread into numerous wider cracks.
Figure 2.2.7(a) shows typical flexure, shear, axial and torsional cracks due to
applied external load.
External restraint forces are generated if the free movement of the concrete in
response to the effects of temperature, creep and shrinkage is prevented from
occurring due to restraint at the member supports. The restraint may consist of
friction at the bearings, bonding to already hardened concrete, or by attachment to
other components of the structure. Cracks resulting from the actions of external
restraint forces develop in a similar manner as those due to externally applied
loads. Figure 2.2.7(b) shows restraint induced cracking due to an increase in
temperature of the top surface of a beam.
Internal restraint forces are caused by the differential expansion or contraction
of the exterior surface of concrete relative to the interior mass of the concrete,
as in plastic shrinkage. The resulting surface cracks are normally shallow and
appear as pattern cracks, checking and D-cracks. Figure 2.2.7(c) shows medium
pattern cracking in an abutment wall.
1-2-6
These internal forces may also be caused by carbonation of concrete. The calcium from the concrete reacts with
carbonic acid (which occurs when the carbon dioxide in the air combines with moisture) resulting in a volume
decrease. This volume decrease occurs only in the outer layer of the concrete, but usually hairline pattern cracks
and a surface discolouration result.
Differential movements or settlements result in the redistribution of external reactions and internal forces in the
structure. This may in turn result in the introduction of additional tensile stresses and, therefore, cracking in the
concrete components of the structure. Movement cracks may be of any orientation and width, ranging from fine
cracks above the reinforcement due to formwork settlement, to wide cracks due to foundation or support
settlement. Figure 2.2.7(d) shows movement induced cracks.
Corrosion of reinforcement produces cracks as described in 2.2.4. Corrosion related cracks are shown in Figure
2.2.7(e).
Severity
Hairline cracks - less than 0.1 mm wide.
Narrow cracks
Medium cracks
Wide cracks
2.2.8
- 0.1 mm to 0.3 mm wide.
- 0.3 mm to 1.0 mm wide.
- greater than 1.0 mm wide.
ALKALI-AGGREGATE REACTION (AAR)
In Ontario, there exists several sources of aggregates that react adversely with the alkalis in cement to produce a
highly expansive gel. Currently, these sources of reactive aggregates are generally avoided, but they do exist in
many existing structures and still may occur in newer structures. The two general types of reactions in Ontario
are alkali-carbonate and alkali-silica reaction. The expansion of the gel and aggregates occurs due to hydroxyl
ions in the concrete pore solution, which under moist conditions, leads to cracking and deterioration of the
concrete. Normally, higher alkali content of the cement and higher cement content of the concrete will lead to a
higher rate of expansion and cracking. The cracking occurs through the entire mass of the concrete (Reference
1). Alkali-aggregate reactions are generally slow by nature, especially at the start, and the results may not be
apparent for many years. Once the alkali-aggregate reaction starts, there are no remedial measures to stop or
reverse the process of deterioration. However, sealing the surface to reduce the moisture infiltration does slow
down the reaction. The appearance of concrete affected by alkali-aggregate reactions is shown in Figure 2.2.8.
Severity
Light
- Hairline pattern cracks, widely spaced, with no visible expansion of the concrete mass.
Medium - Narrow pattern cracks, closely spaced, with visible expansion of the concrete mass.
Severe
- Medium to wide pattern cracks, closely spaced, with visible expansion and deterioration of
concrete.
Very
Severe
- Wide pattern cracks, closely spaced, with extensive expansion and deterioration of concrete.
Apr. 2008
1-2-7
2.2.9
SURFACE DEFECTS
The following surface defects in concrete are described herein:
-
Stratification;
Segregation;
Cold Joints;
Deposits - efflorescence, exudation, incrustation, stalactite;
Honeycombing;
Pop-outs;
Abrasion and Wear;
Slippery Surface.
Surface defects are not necessarily serious in themselves; however, they are indicative of a potential weakness in
the concrete, and their presence should be noted but not classified as to severity, except for honeycombing and
pop-outs.
STRATIFICATION is the separation of the concrete components into horizontal layers in over-wetted or overvibrated concrete. Water, laitance, mortar and coarse aggregates occupy successively lower positions. A layered
structure in concrete will also result from the placing of successive batches that differ in appearance.
SEGREGATION is the differential concentration of the components of mixed concrete resulting in nonuniform proportions in the mass. Segregation is caused by concrete falling from a height, with the coarse
aggregates settling to the bottom and the fines on top. Another form of segregation occurs where reinforcing
bars prevent the uniform flow of concrete between them.
COLD JOINTS are produced if there is a delay between the placement of successive pours of concrete, and if
an incomplete bond develops at the joint due to the partial setting of the concrete in the first pour.
DEPOSITS are often left behind where water percolates through the concrete and dissolves or leaches chemicals
from it and deposits them on the surface. Deposits may appear as the following:
Efflorescence
-
a deposit of salts, usually white and powdery.
Exudation
-
a liquid or gel-like discharge through pores or cracks in the surface.
Incrustation
-
a hard crust or coating formed on the concrete surface.
Stalactite
-
a downward pointing formation hanging from the concrete surface, usually
shaped like an icicle.
HONEYCOMBING is produced due to the improper or incomplete vibration of the concrete which results in
voids being left in the concrete where the mortar failed to completely fill the spaces between the coarse
aggregate particles. Figure 2.2.9 shows medium honeycombing in the underside of a deck slab.
1-2-8
Nov. 2003 Revision
Severity
Light
- Honeycombing to a depth less than 25mm.
Medium- Honeycombing to a depth between 25mm and 50mm.
Severe - Honeycombing to a depth between 50mm and 100mm.
Very - Honeycombing to a depth greater than 100mm.
Severe
POP-OUTS are shallow, typically conical depressions, resulting from the breaking away of small portions of the
concrete surface, due to the expansion of some aggregates or due to frost action. The shattered aggregate
particle may be found at the bottom of the depression, with a part of the aggregate still adhering to the pop-out
cone.
Severity
Light
- Pop-outs leaving holes up to 25 mm in depth.
Medium- Pop-outs leaving holes between 25 mm and 50 mm in depth.
Severe - Pop-outs leaving holes between 50 mm and 100 mm in depth.
Very - Pop-outs leaving holes greater than 100 mm in depth.
Severe
ABRASION is the deterioration of concrete brought about by vehicles or snow-plough blades scraping against
concrete surfaces, such as, decks, curbs, barrier walls or piers.
WEAR is usually the result of dynamic and/or frictional forces generated by vehicular traffic, coupled with the
abrasive influx of sand, dirt and debris. It can also result from the friction of ice or water-borne particles against
partly or completely submerged members. The surface of the concrete appears polished.
SLIPPERY CONCRETE SURFACES may result from the polishing of the concrete deck surface by the
action of repetitive vehicular traffic.
Severity
There are no severity descriptions given for slippery concrete surfaces as this is a serious and potentially
hazardous situation. Where evidence of slippery concrete deck surface is noted the District and Regional Traffic
Offices shall be notified.
Apr. 2008
1-2-9
Nov. 2003 Revision
Figure 2.2.1 Severe Scaling in a Concrete Deck and Curb
Figure 2.2.2 Very Severe Disintegration of Concrete
in Exterior Face
1-2-10
Figure 2.2.3 Very Severe Erosion of a Concrete Footing
salt laden water
Cracks produced
due to increase in
volume of rusted
reinforcing steel
Water seeps into
concrete through
capillary action
rust formation
reinforcing steel
Figure 2.2.4(a) Process Leading to Corrosion of Reinforcement
1-2-11
Figure 2.2.4(b) Light Stains on Concrete Surface
Indicating Corrosion of Reinforcement
Figure 2.2.5 Very Severe Spalling and Delamination in
Concrete Beams
1-2-12
Figure 2.2.6(a) Very Severe Spalling in a Concrete
Pier Cap Due to Corrosion of Reinforcement
Figure 2.2.6(b) Severe Local Spalling
1-2-13
Flexure Cracks
Shear Cracks
Torsion Cracks
Axial Cracks
Figure 2.2.7(a) Applied Loading Cracks
Figure 2.2.7(b) External Restraint Induced Cracks
(due to temperature increase in top surface of beam)
1-2-14
Figure 2.2.7(c) Medium Pattern Cracks in an Abutment
Figure 2.2.7(d) Very Wide Movement Crack in an Abutment
1-2-15
Figure 2.2.7(e) Medium Cracks due to Corrosion of Reinforcement
Figure 2.2.8 Severe Alkali-Aggregate Reaction
1-2-16
Figure 2.2.9 Severe Honeycombing in the Underside of a Deck Slab
1-2-17
2.3 STEEL
The use of steel has progressed from cast iron, wrought iron, rivet steel and plain carbon steel to low alloy atmospheric
corrosion resistant steel (weathering steel) and notch tough low temperature steel.
The following defects commonly occurring in steel are described:
- Corrosion;
- Permanent Deformation;
- Cracking;
- Connection deficiencies.
2.3.1 CORROSION
Corrosion is the deterioration of steel by chemical or electro-chemical reaction resulting from exposure to air, moisture, deicing salts, industrial fumes and other chemicals and contaminants in the environment in which it is placed. The terms rust
and corrosion are used inter-changeably in this sense. Corrosion, or rusting, will only occur if the steel is not protected or if
the protective coating wears or breaks off.
Rust on carbon steel is initially fine grained, but as rusting progresses it becomes flaky and delaminates exposing a pitted
surface. The process thus continues with progressive loss of section.
Weathering steel, on the other hand, will form a relatively smooth rust layer, called a patina, which protects the underlying
metal from further corrosion. However, in less than ideal circumstances, the patina may not form or may be penetrated and
delaminated, resulting in progressive corrosion (References 2,3).
For weathering steel to form a tightly adherent patina, the following conditions must be met:
- the steel must be exposed to intermittent wetting and drying cycles;
- corrosive contaminants, especially salt bearing water, must be absent;
- the steel surfaces must be kept clean and free of entrapped dirt, debris and moisture.
In addition to the above, mill scale is often left on weathering steel to "weather off", except where it is removed for
appearance; however, if the mill scale is scratched, then the underlying metal may corrode.
Corrugated Steel Pipe culverts (CSP’s) and Multi-Plate culverts experience rusting after the protective galvanizing
coating has worn off. This rusting is often most prevalent near the waterline where the abrasive action of the water
prematurely wears away the coating and the steel is subject to high humidity.
Corrosion in steel is illustrated in Figure 2.3.1.
Severity
Light
Medium
-
Severe
Very Severe
-
Loose rust formation and pitting in the paint surface. No noticeable section loss
Loose rust formation with scales or flakes forming. Definite areas of rust are noticeable. Up
to 10% section loss.
Stratified rust with pitting of the metal surface. Between 10% to 20% section loss.
Extensive rusting with local perforation or rusting through. In excess of 20% section loss.
Apr. 2008
1-2-18
2.3.2 PERMANENT DEFORMATIONS
Permanent deformation of steel members can take the form of bending, buckling, twisting or elongation, or any combination
of these. Permanent deformations may be caused by overloading, vehicular collision, or inadequate or damaged
intermediate lateral supports or bracing. See Figure 2.3.2.
Permanent bending deformations occur in the direction of the applied loads and are usually associated with flexural
members; however, vehicular impact may produce permanent deformations in bending in any other member.
Permanent buckling deformations normally occur in a direction perpendicular to the applied load and are usually associated
with compression members. Buckling may also produce local permanent deformations of webs and flanges of beams, plate
girders or box girders.
Permanent twisting deformations appear as a rotation of the member about its longitudinal axis and are usually the result of
eccentric transverse loads on the member.
Permanent axial deformations occur along the length of the member and are normally associated with applied tension loads.
In Corrugated Steel Pipe culverts (CSP’s) and Multi-Plate culverts some degree of deformation can be tolerated due to
the continuity of the steel plate along the culvert length. Deformations in culverts can include the following:
- Cusping: The abrupt change in curvature of the culvert wall, typically at a longitudinal seam, leading to a
lifting of adjacent plates and usually caused by improper installation of bolts (lack of torque) or poor backfill
compaction. Cusping usually leads to other defects since the culvert is not in its design shape and significant
bending stresses can occur.
- Crimping: The local buckling of culvert wall (usually near areas of higher curvature) primarily due to
bending forces.
- Bolt Tilting: The bearing failure of the culvert wall at the location of the bolt holes. Initially, the bolts tilt as
the inner and outer plates of the culvert move against each other. As it progresses, it often leads to cracking
at the bolt holes.
- Global deformations: These distortions usually occur on the roof or sometimes on the floor of the culvert. It
is caused by the weight of soil or live load when the roof deforms or due to soil or hydrostatic pressures from
below when the floor deforms. Often, it is caused by improper installation and the deformation can be
tolerated if the movement has stabilized – this should be ascertained by monitoring. It is more serious when
there is reverse curvature of the culvert. The culvert wall relies on its curved shape to maintain the internal
forces as primarily axial thrust (and not bending) and the wall relies on curvature into the soil to provide
lateral support for the culvert wall in compression.
Severity
Steel
Members
-
As permanent deformations may be critical to the integrity of the member and/or structure, all
permanent deformations in steel members shall be categorized as a Severe defect. The
location of the deformation within the member, and the location of the member in the structure,
should be recorded.
Photographs and measurements of the amount and extent of deformation shall be taken and
recorded for analysis by an engineer.
Steel Culverts
-
Medium
-
-
Severe
-
Bolt Tilting,
Crimping or cusping < 10 mm height.
Any deformation < 10% of diameter.
Crimping > 10 mm height.
Any deformation >10% of diameter.
Any deformation causing reverse curvature.
1-2-19
Apr. 2008
2.3.3 CRACKING
CRACK is a linear fracture in the steel. Cracks are mainly produced due to fatigue and can, under certain conditions, lead
to a brittle fracture.
BRITTLE FRACTURE is a crack completely through the component that usually occurs without prior warning or plastic
deformation. Brittle fracture may result at fatigue prone details after initial fatigue cracking.
FATIGUE PRONE DETAILS are those details that are susceptible to the growth of fatigue cracks. Details in fatigue
stress categories E and F, which are most susceptible to fatigue crack growth, are illustrated in references 9 and 10.
FRACTURE CRITICAL COMPONENTS are components which are subject to tensile stresses in a single load path
structure and whose failure could lead to collapse of the structure. Any attachment having a length in the direction of
tension stress greater than 100 mm. and that is welded to the tension area of a fracture critical component shall also be
considered as fracture critical.
The primary factors leading to fatigue cracking are: the number of applied stress cycles, which is a function of the volume
of traffic; the magnitude of the stress range, which depends on the applied live load; and the fatigue strength of the
connection detail, category A to W, as given in the Ontario Highway Bridge Design Code, reference 10. Cracks caused by
fatigue usually occur at points of tensile stress concentrations, at welded attachments or at termination points of welds.
Cracks may also be caused or aggravated by overloading, vehicular collision or loss of section resistance due to corrosion.
In addition, stress concentrations due to the poor quality of fabricated details and the fracture toughness of materials used
are contributing factors. Material fracture toughness will determine the size of crack that can be tolerated before fracture
occurs.
Welded details are more prone to cracking than bolted or riveted details. Grinding off the weld reinforcement to be smooth
or flush with the joined metal surfaces improves fatigue resistance. Once cracking occurs in a welded connection, it can
extend into other components due to a continuous path provided at the welded connection, and possibly lead to a brittle
fracture.
Bolted or riveted connections may also develop fatigue cracking, but a crack in one component will generally not pass
through into the others. Bolted and riveted connections are also susceptible to cracking or tearing resulting from prying
action, and by a build-up of corrosion forces between the parts of the connection.
Cracking which has resulted in a brittle fracture in a diaphragm beam is shown in Figure 2.3.3(a).
Common locations susceptible to cracking are illustrated in Figure 2.3.3(b). As cracks may be concealed by rust, dirt or
debris, the suspect surfaces should be cleaned prior to inspection.
In Corrugated Steel Pipe culverts (CSP’s) and Multi-Plate culverts some degree of cracking at bolt hole locations may
be tolerated due to the continuity of the steel plate along the culvert length. For this reason, cracks at bolt holes may
not require repair as urgently as cracks in steel bridge members. These cracks can occur due to improper installation or
due to higher bending or compressive forces in the culvert walls.
Severity
Steel
Members
-
Cracks that are parallel with the direction of stress are usually not as serious; however, those
perpendicular to the direction of stress are very serious. In either case, cracks in steel should
generally be considered serious, as a parallel crack may, for a number of reasons, turn into a
perpendicular crack. Therefore all cracks shall be categorized as a Severe defect. Immediate
action is required when cracks are noticed (i.e. notify bridge owner). Any crack should be
carefully noted and recorded as to its specific location in the member, and member in the
structure. The length, width (if possible) and direction of crack should also be recorded.
Steel Culverts
-
Severe
-
All Cracks beside bolts.
1-2-20
(a)
Apr. 2008
2.3.4 CONNECTION DEFICIENCIES
Loose connections can occur in bolted, riveted or clamped connections. The loose condition may be caused by
corrosion of the connector, gusset plates or fasteners, cracking or failure of the individual fasteners, excessive
vibration, over stressing, or simply a lack of proper tightening during construction.
Loose connections may not always be detectable by visual or hands-on inspection, as the looseness may only
appear during serviceability loading. Cracking or excessive corrosion of the connector or gusset plates or the
fasteners, as well as permanent deformation of the connection or members framing into it, may be indications of
loose connections. Also, fasteners with missing washers or improper thread engagement are more susceptible to
becoming loose over time, and should be inspected more closely. Tapping the connection with a hammer is one
method of determining if the connection is loose.
The other deficiencies typically associated with connections are corroded or cracked connectors or gusset plates.
Severity
The severity of the connection deficiency shall be based on the condition of the worst component within the
connection. This means that the connection will be rated based on the looseness or corrosion of the worst
component. In the case of truss members, the connection shall be taken as the entire joint or node location,
including both gusset plates in and out of plane, with all members that frame in. All connecting member plates
shall be inspected with the overall connection rating based on the worst of these components. For Bailey
Bridges, the Bailey panel connection pin shall be rated as a connection. The other connections, such as transom
clamps and raker pins are too numerous to rate individually. They still should be inspected, but problems should
be noted as either a maintenance need or a performance deficiency (as described in Section 5 and 6 of Part 2) for
the floor beam or truss bracing elements respectively.
The location of the loose or missing fasteners, as well as areas of corrosion on gusset plates, should be described.
The severity can be determined as outlined below for the various components within the connection:
1.
The severity of loose connections depends largely on the number of loose or missing fasteners relative
to the total number in the connection. The severity description involves the determination of this ratio.
2.
The severity of gusset plates depends on the amount of severe or very severe corrosion or cracks relative
to the total plan area. The severity description involves this ratio.
Table 2.2: Severity of Connection Deficiency for Connections in Steel
Connection Deficiency
Loose Fasteners
Light
Medium
Severe
< 5% Loose
5 to 10% Loose
> 10% Loose
Gusset Plate with Severe or Very
Severe Corrosion or Cracks
< 5% of Plan Area
5 to 10% of Plan Area
> 10% of Plan Area
Oct.
Apr.2000
2008
1-2-20
(b)
Figure 2.3.1
Figure 2.3.2
Medium Corrosion of Steel Beams
Very Severe Permanent Deformations by Impact
1-2-21
Figure 2.3.3(a)
Very Wide Cracks in a Diaphragm
1-2-22
Web
Crack
Web
Splice
Web
Hole
Crack
Crack at Hole in Web
Crack in Web at Web Splice
Web Splice
Web
Flange
Splice
Crack
Crack
Cope
Crack in Cope of Web at a Connection
Crack in Flange at Flange Splice
Stiffener
Cover
Plate
Crack
Web
Web
Crack
Flange
Crack in Web at Stiffener
Figure 2.3.3(b)
Crack at End Weld of Flange
Cover Plate
Common Crack Locations in Steel
1-2-23
Stiffener
Crack
Web
Floorbeam
Crack
Tension Flange
Girder Web Crack Between Cut-Short
Stiffener and Tension Flange
Crack in Web of Floor Beam at
Cut-Short Tension Flange
Flange
Crack
Crack
Web
CrossBracing
Connection
Plate
Girder Web Crack Behind Chamfer
of Connection Plate
Crack in Cross-Bracing
Connection Plate
Stiffener
Web
Crack
Gusset
Plate
Flange
Crack at Web to
Stiffener Weld
Flange
Crack at Flange
to Web Weld
Vertical Web Crack Behind Chamfer
of Horizontal Gusset Plate
Stiffener
Plate
Cracks at Double Curvature in Web
Plate From Flange Movements
Figure 2.3.3(b)
Common Crack Locations in Steel (cont'd)
1-2-24
2.4
WOOD
Wood was one of the earliest materials used for structures, and is still in common
use today. This is largely due to its availability in a variety of structural
sizes and ease of handling.
The following defects commonly occurring in wood are described:
-
Checks, Splits and Shakes;
Weathering;
Rot or Decay;
Insect Damage;
Abrasion and Wear;
Cracking, Splintering, Crushing and Shattering;
Fire and Chemical Damage;
Connection Deficiencies.
2.4.1
CHECKS, SPLITS AND SHAKES
Checks are longitudinal tissue separations on the side grain of wood members,
occurring across or through the annual growth rings.
Splits are similar to checks, with more severe tissue separations, extending either
through the wood member or from the side into the end grain, typically at the ends of
the wood member.
Shakes are tissue separations which follow the circular annual growth rings, and
are usually visible on the end grain.
Checks, splits and shakes are illustrated in Figure 2.4.1(b).
Severity
Light
Medium
Severe
Very Severe
2.4.2
-
Checks, splits or shakes that extend for less than 5% into the member.
Checks, splits or shakes that extend for between 5% and 10% into the member.
Checks, splits or shakes that extend for between 10% and 20% into the member.
Checks, splits or shakes that extend for more than 20% into the member.
WEATHERING
Weathering is the gradual deterioration of wood due to exposure to the actions of
sun, rain, wind, frost and atmospheric pollutants. Weathering of untreated wood is
accompanied by softening of the surface layer and a grey discolouration and "barnboard" appearance. Treated wood weathers more slowly to a gray-brown colour and
may exhibit a rough "wash-board" appearance. Light weathering is shown in Figure
2.4.1(a).
1-2-25
Apr. 2008
Severity
Light
Medium
Severe
Very Severe
2.4.3
-
Slight surface weathering with less than 5% section loss.
Surface weathering with 5% to 10% section loss.
Loss of section between 10% and 20%.
Loss of section greater than 20%.
ROT OR DECAY
Rot or decay is the biological decomposition of wood caused by micro-organisms called
fungi. Rot develops in progressive stages, usually through cracks, knots, holes and at
the ends of members. The growth of fungi requires the presence of adequate moisture, a
supply of oxygen and a favourable (warm) temperature. The absence of any of these
factors will greatly inhibit or prevent fungal growth.
The most common method of
reducing rot or decay in wood is by pressure treatment with preservatives.
The
-
following areas are typically prone to decay:
Wood in contact with soil;
Wood at the water line;
Surfaces in contact where water can be trapped, such as, connections and bearing
areas;
- At checks,splits, shakes and cracks, through which moisture can penetrate the wood.
- At the centre core of wood, especially for piles;
Three types of rot may be identified in wood; namely, white rot, brown rot and soft
rot.
White rotted wood has a bleached appearance, and in advanced stages the wood appears as
a grey fibrous mass. It develops at or above ground contact and may attack both the
surface and interior portions of wood.
Brown rotted wood has a reddish-brown appearance, and in advanced stages the wood has a
checked or crumbly surface. It develops at or above ground contact and may attack both
the surface and interior portions of wood.
Soft rotted wood has a soft, spongy surface, and in advanced stages the wood has a
charred appearance. It usually develops below ground level or under water, and usually
attacks only the surface of the wood.
The surface appearance of rotted wood is shown in Figure 2.4.2.
Severity
Light
- Slight change in colour. The wood sounds solid and cannot be penetrated by a sharp
object*. Damage is superficial with less than 5% section loss.
Medium
- Surface is discoloured with black and brown streaks. The wood sounds solid when
tapped and offers moderate resistance to penetration by a sharp object*. Noticeable
damage with 5% to 10% section loss.
Severe
- Surface is fibrous, checked or crumbly and fungal fruiting bodies are growing on it.
The wood sounds hollow when tapped and offers little resistance to penetration by a
sharp object*. Considerable damage with 10% to 20% section loss
Very Severe
- The wood can be crumbled and disintegrated with ease*. Extensive damage with
section loss in excess of 20%.
*For older timber, especially when in contact with water, coring or drilling may be required to
confirm the presence of rot identified by sounding (see Part 4, Section 2).
1-2-26
Apr. 2008
2.4.4
INSECT DAMAGE
Defects in wood caused by insects are a consequence of the tunnelling and boring by
larvae or mature insects through the wood resulting in loss of section. Termites,
carpenter ants and wood-boring beetles are the most common insects that attack wood
in Ontario.
Their appearance is shown in Figure 2.4.3(a), and the resulting
appearance of insect damaged wood is shown in Figure 2.4.3(b).
The severity of the insect damage can be judged by the number of holes and tunnels
on the surface of the wood and by the number of insects around the area.
Severity
Light
Medium
Severe
Very Severe
2.4.5
- Occasional entrance or exit holes are present. The wood is solid and cannot be easily
penetrated by a sharp object. Less than 5% section loss.
- Several entrance or exit holes are visible, and larvae or mature insects may be
observed. The wood sounds generally solid when tapped, and offers moderate
resistance to penetration by a sharp object. 5% to 10% section loss.
- Extensive tunnelling and holes are present in the wood. Larvae and insects are
readily visible. The wood sounds hollow when tapped, and offers little resistance to
penetration by a sharp object. 10% to 20% section loss.
- Extensive tunnelling, holes, larvae and insects present. Wood can be crumbled and
is disintegrated with ease. Greater than 20% section loss.
ABRASION AND WEAR
Abrasion is the deterioration of wood brought about by vehicles or snowplough
blades scraping against wood surfaces, such as, decks, curbs, railings or piers.
Wear is usually the result of dynamic and/or frictional forces generated by
vehicular traffic, coupled with the abrasive influence of sand, dirt or debris. It
can also result from the friction of ice or water-borne particles against partly or
completely submerged members. The surface of the wood appears worn and cracked with
some loss of section. Wear of a wood deck and abrasion by ice are illustrated in
Figures 2.4.4(a) and 2.4.4(b) respectively.
Severity
Light
- Slight surface wear with less than 5% section loss.
Medium
- Surface wear more noticeable with 5% to 10% section loss.
Severe
- Loss of section between 10% to 20%.
Very Severe
- Loss of section in excess of 20%.
1-2-27
Apr. 2008
2.4.6
CRACKING, SPLINTERING, CRUSHING AND SHATTERING
Cracking, splintering, crushing and shattering are forms of physical damage which
result from vehicular collision or from overloading of a member. Particularly
susceptible are members already weakened by rot or insect attack.
A crack is an incomplete separation of the wood into two or more parts with or
without space in between. Cracking across the grain is caused by flexural damage
through overloading. Cracking along the grain may be due to shear failure or a
continuation of a split.
Splintering is a series of localized tensile failures in the wood where fragmented
parts of the wood may protrude from the surface.
Crushing is a form of permanent deformation where a portion of the wood has lost
its resiliency to rebound. Crushing at the bearings occurs due to excessive
compression. Crushing may also occur prior to a flexural failure.
Shattering is a combined form of crushing and splintering resulting from impact.
Crushing and splintering of wood due to vehicular impact is shown in Figure 2.4.5.
Severity
Light
- Damage is mainly superficial with less than 5% section loss.
Medium
- Considerable damage with 5% to 10% section loss.
Severe
- Significant damage with 10% to 20% section loss.
Very
Severe
- Extensive damage with section loss in excess of 20%.
2.4.7
FIRE AND CHEMICAL DAMAGE
Fire damage is evidenced by charring and is usually confined to the wood surface.
Connectors may sustain more damage from fire than the members connected. Such
damage to connections is manifested by large deformations of the connector plates
and fasteners, and by loose or misaligned joints.
Chemical damage may result from the use of non-preservative chemicals on the wood
surface over a long period of time, or where the wood comes in contact with
corrosive chemicals resulting from accidental spills. Such damage affects the wood
surface and metal connectors. The effect of chemicals on the wood is a softening
of the surface accompanied by loss of strength. The effect on metal connector
plates and fasteners is less critical except in certain circumstances; for example,
on fasteners with low corrosion resistance.
Figures 2.4.6(a) and 2.4.6(b) shows fire and chemical damaged wood.
1-2-28
Apr. 2008
Severity
Light
- Slight charring or softening of the wood surface with less than 5%
section loss. Connectors unaffected.
- Deeper charring or softening with 5% to 10% section loss.
Connectors slightly loosened.
- Section loss between 10% and 20% with several connectors loosened
or deformed.
- Extensive damage with section loss greater than 20% at critical
locations. Many loose and severely deformed connectors.
Medium
Severe
Very
Severe
2.4.8 CONNECTION DEFICIENCIES
Wood members are normally connected with common nails, spikes, bolts, shear plates, split rings, metal framing
connectors or glulam rivets. Most connections are loosened due to repetitive or dynamic loads, wear or decay of
members connected, and corrosion of the connectors.
appear during serviceability loading. Cracking or excessive corrosion of the plates or fasteners, as well as
permanent deformation of the connection or members framing into it, may be indications of loose connections.
A loose connection joining wood members is shown in Figure 2.4.7.
Severity
connection. This means that the connection will be rated based on the looseness, decay or corrosion of the worst
including both gusset plates in and out of plane, with all members that frame in to the connection.
The location of the loose or missing fasteners, as well as areas of corrosion any gusset plates, should be
described. Any unintended gaps that are observed should be measured and recorded.
1.
The severity of loose connections depends largely on the number of loose or missing fasteners
relative to the total number in the connection. The severity description involves the
determination of this ratio.
2.
The severity of gusset plates depends on the amount of severe or very severe corrosion or cracks
relative to the total plan area. The severity description involves this ratio.
Table 2.4: Severity of Connection Deficiency for Connections in Wood
Light
Medium
Severe
Loose Fasteners
< 5% Loose
5 to 10% Loose
> 10% Loose
< 5% of Plan Area
> 10% of Plan Area
Apr. 2008
1-2-29
Figure 2.4.1(a)
Light Weathering in Wood Members
CENTRE
CHECK
END
CHECK
SHAKE
CHECK
Figure 2.4.1(b)
Checks, Shakes and Splits in Wood
1-2-30
SPLIT
Figure 2.4.2
Termite
Very Severe Brown Rot
Carpenter Ant
Figure 2.4.3(a)
Wood Boring Beetle
(Larva and Adult)
Wood Boring Insects
1-2-31
Figure 2.4.3(b)
Figure 2.4.4(a)
Very Severe Insect Damage in Wood
Very Severe Wear in a Wood Deck
1-2-32
Figure 2.4.4(b)
Very Severe Abrasion on a Wood Pile Due to Ice
Figure 2.4.5 Very Severe Crushing and Splintering
of Wood Due to Vehicular Impact
1-2-33
Figure 2.4.6(a)
Medium Fire Damage on Wood
1-2-34
Figure 2.4.6(b)
Light Chemical Damage on Underside
of a Wood Deck
Figure 2.4.7 Loose Connection in Wood
(25 mm gap measured)
1-2-35
2.5
MASONRY
Masonry is made of stones or bricks bonded together by mortar. Although not a common construction material
today, masonry was used in Ontario, usually in retaining walls, abutments, piers or arches, primarily in the 19th
century while brick masonry was only rarely used in highway structures. Types of masonry construction are
ashlar masonry, squared stone masonry and rubble masonry.
The following defects commonly occurring in masonry are described:
-
2.5.1
Cracking;
Splitting, Spalling and Disintegration;
Loss of Mortar and Stone.
CRACKING
A crack is an incomplete separation into one or more parts with or without space in between. Cracks develop in
masonry as a result of non-uniform settlement of the structure, thermal restraint, frost action and overloads.
Cracks develop either at the interface between the stone and mortar, following a zig-zag pattern, when the bond
between them is weak; or, go through the joint and stone, in a straight line, when the mortar is stronger than the
stone, as shown in Figure 2.5.1.
Severity
Hairline cracks - less than 0.1 mm wide.
Narrow cracks
Medium cracks
Wide cracks
2.5.2
- between 0.1 and 0.3 mm wide.
- between 0.3 and 1.0 mm wide.
- greater than 1.0 mm wide.
SPLITTING, SPALLING AND DISINTEGRATION
SPLITTING
is the opening of seams or cracks in the stone leading to the breaking of the stone into large
fragments.
SPALLING
is the breaking or chipping away of pieces of the stone from a larger stone.
DISINTEGRATION is the gradual breakdown of the stone into small fragments, pieces or particles.
1-2-36
Nov. 2003 Revision
The splitting, spalling and disintegration of masonry is caused by the actions of frost, weathering and
abrasion; or, by the actions of acids, sulphates or chlorides, which cause deterioration in certain types of
stones, such as
limestone. The splitting, spalling and disintegration of masonry are shown in Figure 2.5.2.
Severity
Light
-
Hairline cracking and minor loss of stone surface with loss of section up to 50 mm.
Medium-
Narrow cracking or chipping away of stone with loss of section between 50 and 100 mm.
Severe -
Spalling and disintegration of stone with loss of section between 100 and 150 mm.
Very Severe
Extensive spalling and disintegration of stone with loss of section in excess of 150 mm.
2.5.3
LOSS OF MORTAR AND STONES
Loss of mortar is the result of the destructive actions of frost, erosion, plant growth or softening by water
containing dissolved sulphates or chlorides. Once the mortar has disintegrated it may lead to loss of stones.
It should be noted that some structures have been built without the use of mortar.
Figure 2.5.3 shows evidence of loss of mortar in a masonry arch.
Severity
Light
-
Mortar lost from the joints in a few places, to a depth of 20 mm.
Medium-
Mortar lost from the joints over an extended area, to a depth between 20 and 50 mm.
Severe -
Extensive loss of mortar resulting in the loss of a few stones.
Very Severe
Extensive loss of stones endangering the stability of the structure.
1-2-37
Figure 2.5.1
A Wide Crack Through the Stone in a Masonry Pier
Figure 2.5.2
Very Severe Splitting, Spalling and
Deterioration in Masonry.
1-2-38
Figure 2.5.3
Very Severe Loss of Mortar and Stone
in a Masonry Arch
1-2-39
2.6
ALUMINUM
Aluminum is often used in railings, splash guards, drainage systems, signs and
sign supports.
The following defects commonly occurring in aluminum are described:
-
Corrosion;
Cracking;
Connection deficiencies.
2.6.1
CORROSION
Corrosion in aluminum is usually a uniform, gradual oxidation of the surface in the
presence of air and moisture.
Aluminum has a strong resistance to corrosion
deterioration after the initial formation of aluminum oxide, a dense and very
adherent film, which protects the underlying metal and inhibits further corrosion.
However, in less than ideal circumstances this protective layer may fail to form,
or be penetrated and broken down to expose the underlying metal. The process of
corrosion will then continue with progressive loss of section.
Factors which affect this are the presence or exposure of the aluminum to de-icing
salts, industrial fumes, water containing dissolved chemicals, bird droppings and
surface scratches. Tight corners, especially around joints and connections, which
entrap moisture and debris are, particularly, susceptible to progressive corrosion.
In addition, contact with other metals and concrete results in galvanic and
chemical corrosions.
GALVANIC CORROSION occurs at bi-metal joints. Where aluminum comes in contact with
other metals a galvanic cell is formed in the presence of an electrolyte, such as a
salt solution, resulting in the localized corrosion of the aluminum. Galvanic
corrosion may affect the formation of the protective aluminum oxide film or cause
the film to flake off. It is, therefore, necessary that an inert spacer, either
nylon or neoprene, be placed between the two metals to prevent galvanic corrosion.
Galvanic corrosion does not occur when aluminum is in contact with galvanized or
stainless steel.
CHEMICAL CORROSION refers to the corrosion which takes place when aluminum comes in
contact with concrete. When this happens a chemical reaction takes place between
the aluminum and lime in the concrete which leads to progressive corrosion of the
aluminum and loss of section. An inert spacer or bitumastic coating should be used
between the concrete and aluminum to prevent chemical corrosion.
Figure 2.6.1 shows typical corrosion in aluminum.
1-2-40
Apr. 2008
Severity
Light
- Discolouration, grey to grey-black mottled appearance. Roughened
surface with light blistering. No noticeable loss of section.
Medium
- Definite areas of corrosion are noticeable. Moderate blistering
and surface pitting. Up to 10% loss of section.
Severe
- Extensive blistering and overall pitting.
section.
Very
Severe
- Very extensive blistering and overall pitting.
section.
2.6.2
10% to 20% loss of
Over 20% loss of
CRACKING
A crack is a linear fracture in the aluminum which may extend partially or
completely through the material. Cracks normally develop as a result of fatigue
followed by brittle fracture and excessive corrosion. Cracks may also be produced
by freezing of entrapped water. Cracks initiate from either the inside or the
outside surface of a member and become visible as hairline cracks on the surface.
As cracks may be concealed by corrosion by-products, dirt or debris, the suspect
surfaces should be cleaned prior to inspection. A crack in an aluminum component
is illustrated in Figure 2.6.2.
Severity
Because of the difficulty in measuring crack widths in aluminum no severity
description has been established for cracks. Rather, a general report as to the
occurrence and extent of cracks should be made which identifies the location,
length and width of cracks wherever possible.
2.6.3
CONNECTION DEFICIENCIES
Loose connections can occur in bolted, riveted or clamped connections. The loose condition may be caused by
corrosion of the gusset plates or fasteners, cracking or failure of the individual fasteners, excessive vibration,
over stressing, or simply a lack of proper tightening during construction.
appear during serviceability loading. Cracking or excessive corrosion of the connector, gusset plates fasteners,
as well as permanent deformation of the connection or members framing into it, may be indications of loose
connections. Also, fasteners with missing washers or improper thread engagement are more susceptible to
becoming loose over time, and should be inspected more closely. Tapping the connection with a hammer is one
method of determining if the connection is loose.
The other deficiencies typically associated with connections are corroded or cracked gusset plates.
Oct. 2000
1-2-41
Severity
connection. This means that the connection will be rated based on the looseness or corrosion of the worst
including both gusset plates in and out of plane, with all members that frame in. Each connecting member
and the gusset plates shall be inspected with the overall connection rating based on the worst of these
components.
The location of the loose or missing fasteners, as well as areas of corrosion on gusset plates, should be
described.
1.
The severity of loose connections depends largely on the number of loose or missing fasteners
relative to the total number in the connection. The severity description involves the determination of
this ratio.
2.
The severity of gusset plates depends on the amount of severe or very severe corrosion or cracks
relative to the total plan area. The severity description involves this ratio.
Table 2.6:
Severity of Connection Deficiency for Connections in Aluminum
Loose Fasteners
Light
Medium
Severe
< 5% Loose
5 to 10% Loose
> 10% Loose
1-2-42
< 5% of Plan Area
> 10% of Plan Area
Oct. 2000
Figure 2.6.1
Figure 2.6.2
1-2-43
Light Corrosion
Wide Crack
2.7 ASPHALT PAVEMENT
Asphalt pavement is often used as a wearing surface on concrete, steel and wood decks. The asphalt surface
provides improved safety and riding qualities when compared with a concrete surface, reduces noise, and the
asphalt also offers some protection to the concrete from traffic wear, and the weather. A waterproofing
membrane is also often placed on the deck surface between the deck top surface and the asphalt pavement to
provide protection to the deck surface against the infiltration of moisture and de-icing chemicals, and the
subsequent deterioration or decay.
Wearing Course – Is a dense, highly stable, durable, skid-resistant surface course hot mix asphalt which carries
traffic. It must resist the elements and keep water out of the underlying base material.
Binder Course – The binder course is the lower layer(s) of an asphalt pavement. It is normally distinguished
from the surface course when there is a distinct difference in the quality of the mixtures used. It adds much to the
overall strength of the pavement structure. It supports the surface course and distributes load to the base.
Flexible Pavement – A bituminous surface on a granular base (such as on the approaches of bridges without
approach slabs).
Rigid Pavement – Including composite pavements consist of a concrete slab with bituminous overlays (such as
on a bridge deck or approach slab).
Defects in asphalt pavements can be related to the lack of durability of the asphalt resulting from the composition
of the asphalt, poor placement practices, lack of sub-grade support, reflection cracking, or the aggressive
environment in which it is placed (Reference 4).
Asphalt Defects
Asphalt defects on concrete decks or slabs are sometimes an indication of deterioration of the concrete surface.
For the purposes of bridge inspection, asphalt defects can be grouped into the following two general categories:
(1) Top-Down Defects
• Defects that originate in the asphalt itself, which do not have an appreciable effect on the
concrete deck surface below. These include:
i. Bond Defects (loss of bond and rippling)
ii. Surface Defects (ravelling, slippery surface and flushing)
iii. Surface Distortions (wheel track rutting)
iv. Isolated cracks (Light and medium isolated cracks)
(2) Bottom-up Defects
• Defects that probably originate in the concrete deck and are reflected in the asphalt surface.
These include:
i. Pattern cracking (map, alligator, radial, edge cracking)
ii. Wide isolated cracks (transverse, longitudinal)
iii. Local Underlying Defects (local potholes and protrusions)
2.7.1 CRACKING
A crack is a linear fracture extending partially or completely through the pavement. Cracking in pavements may
be caused by any one or a combination of the following factors; the action of vehicular wheel loading; poor
quality material; poor compaction; placement or quality control; frost action; poor drainage; shrinkage due to low
temperatures; temperature susceptibility of the asphalt cement binder; and as reflection cracks, which are the
extension of cracks in the surface below the pavement.
Cracks are distinguished by their appearance and direction. The following types of cracks are commonly
observed in pavements; longitudinal, transverse, alligator, radial, map, and progressive edge cracking.
1-2-44
Apr. 2008
LONGITUDINAL cracks are roughly parallel to the direction of travel and may be situated at or near the centre
of the wheel tracks, centreline of the roadway, middle of the lane, or along the pavement edges.
TRANSVERSE cracks are approximately at right angles to the pavement centreline and may extend partially or
completely across the pavement.
ALLIGATOR cracks form a network of multi-sided polygons or blocks resembling the skin of an alligator. The
block sizes typically range from 50 mm to 500 mm. They may occur anywhere in the pavement surface, and may
be accompanied by depressions in the surface.
RADIAL cracks in a radial pattern, usually about a depression.
MAP cracks run randomly along the pavement, sometimes in a serpentine manner. They appear to consist of
longitudinal and transverse cracks combined to form a 'map' pattern.
PROGRESSIVE EDGE cracks begin parallel to and usually within 300 mm of the edges of the pavement; such
as, along curb edges and expansion joint end dams. The cracks are either fairly straight and continuous or consist
of crescent-shaped cracks in a wave formation. These cracks may progress significantly into the travelled portion
of the pavement. Edge breaking of the pavement often results from these cracks.
The various types of pavement cracks are illustrated in Figures 2.7.1(a) to 2.7.1(e).
Severity
Light
- 1 mm to 5 mm wide single or multiple cracks;
- alligator pattern established with corners of polygon blocks fracturing;
- progressive edge cracking less than 600 mm from pavement edge, either single or two parallel
cracks.
Medium - 6 mm to 10 mm wide single or multiple cracks;
- alligator pattern established with spalling of polygon blocks;
- progressive edge cracking extending between 600 mm to 900 mm from pavement edges, multiple
cracks with connecting cracks.
Severe
- 10 mm to 20 mm wide single or multiple cracks;
- polygon blocks in alligator cracking are beginning to lift leaving potholes;
- progressive edge cracking extending over 900 mm from pavement edge with alligatoring of
pavement along edges.
Very
Severe
- Greater than 20 mm wide single or multiple cracks;
- a number of polygon blocks lifted off in alligator cracking;
- progressive edge cracking extending over 1200 mm from pavement edge with alligatoring of
pavement along edges.
2.7.2 BOND DEFECTS
2.7.2.1 LOSS OF BOND
Widespread loss of bond and delamination may occur between the asphalt pavement and deck surface, between
the waterproofing and the deck surface, between the waterproofing and asphalt pavement or between individual
lifts of pavement.
Loss of bond and delamination is not directly visible on the pavement surface; however, they may often be
detected by hammer sounding or chain drag. The accurate assessment of the extent or severity of these defects
can usually only be determined by detailed deck survey methods; such as, thermography, radar and removal of the
pavement.
1-2-45
Apr. 2008
Severity
Light
- Loss of bond over area measuring less than 150 mm, in any direction.
Medium - Loss of bond over area measuring between 150 mm and 300 mm, in any direction.
Severe
- Loss of bond over area measuring between 300 mm and 600 mm, in any direction.
Very
Severe
- Loss of bond over area measuring more than 600 mm, in any direction.
2.7.2.2 RIPPLING
Rippling is the formation of transverse undulations in the pavement surface consisting of closely spaced
valleys and crests. Rippling is the result of poor bond of the pavement to the surface below with the
subsequent action of wheel friction and braking forces moving the pavement 'mat' forwards, backwards and
sideways.
Rippling of an asphalt pavement is illustrated in Figure 2.7.6.
Severity
Light
- A few noticeable bumps.
Medium - Several bumps producing a rough ride.
Severe
- Numerous bumps producing a very rough ride with possible loss of vehicle control.
Very
Severe
- Numerous bumps producing a very rough ride with difficulty in maintaining vehicle control
and imminent danger of loss of vehicle control.
2.7.3 LOCAL UNDERLYING DEFECTS
2.7.3.1 POTHOLES
Potholes are bowl-shaped holes in the pavement caused by the penetration of water through the pavement and
the subsequent heaving of the pavement due to freezing of the entrapped water and breaking up of the
pavement due to traffic action. They may result from delaminations or other defects in the underlying
concrete surface. Pavements already deteriorated with such defects as alligator cracking and ravelling are
prone to the occurrence of potholes.
A typical example of a pothole is illustrated in Figure 2.7.4.
Severity
Light
- Holes measuring less than 10 mm in depth.
Medium - Holes measuring between 10 mm to 20 mm in depth.
Severe
- Holes measuring between 20 mm to 40mm in depth.
Very
Severe
- Holes measuring over 40 mm in depth.
Nov. 2003 Revision
1-2-46
2.7.3.2 LOCAL PROTRUSIONS (DELAMINATIONS)
Local delaminations become visible as protrusions or bumps. These are localized upward displacements of
the pavement surface (often circular in shape) typically caused by frost action either between or under the
layers of asphalt. They are generally the initial indications of the formation of potholes.
Severity
Light
- Protrusions measuring less than 10 mm in height.
Medium - Protrusions measuring between 10 mm to 20 mm in height.
Severe
- Protrusions measuring between 20 mm to 40mm in height.
Very
Severe
- Protrusions measuring over 40 mm in height.
2.7.4 SURFACE DEFECTS
2.7.4.1 RAVELLING/SEGREGATION
Ravelling is the progressive deterioration and loss of the pavement material from the surface downward.
Ravelling begins on the surface but progresses down into the asphalt. The surface appears to be breaking up
into small pieces and exposing and eventually loosening the aggregates. Ravelling can occur anywhere over
the surface, but is most common along curb or sidewalk faces where salt-laden roadway drainage collects,
and along wheel tracks due to traffic action on pavements embrittled and weakened through aging. Severe
ravelling may occur together with signs of cracking or potholes.
Ravelling of an asphalt pavement is illustrated in Figure 2.7.2.
Severity
Light
- Noticeable loss of pavement material.
Medium - Shallow disintegration of the pavement surface with an open textured appearance.
Severe
- Shallow disintegration of the pavement surface with small potholes. Very open textured
appearance with loose material over the surface.
Very
Severe
- Deep disintegration of the pavement surface with numerous potholes. Very open textured
appearance with loose material over the surface.
2.7.4.2 FLUSHING
Flushing is the migration of asphalt upwards to the pavement surface in pavements with too much asphalt in
the mix. It commonly occurs in the wheel tracks, especially during hot weather, by the action of vehicle
traffic pressing and squeezing the excess asphalt to the surface. Flushing of the surface of an asphalt
pavement is illustrated in Figure 2.7.7.
Nov. 2003 Revision
1-2-47
Severity
Light
- Visible colouring of the pavement surface occurring in localized areas.
Medium - Distinctive colouring of the pavement surface with excess asphalt free on the pavement surface.
Severe
- Free asphalt gives the pavement surface a 'wet' look; vehicle traffic leaves visible tire marks
and impressions on the pavement surface.
Very
Severe
- Excessive free asphalt on the pavement surface with a 'wet' look. Footprints leave visible
impressions in the pavement surface.
2.7.4.3 SLIPPERY ASPHALT SURFACE
Slippery asphalt surfaces may result from flushing or from the polishing of the coarse surface aggregates by
the action of repetitive vehicular traffic.
Severity
There are no severity descriptions given for slippery surfaces as this is a serious and potentially hazardous
situation. Where evidence of slippery surfaces is noted, a suspected performance deficiency should be
recorded and the District and Regional Traffic Office shall be notified.
2.7.5 SURFACE DISTORTIONS
2.7.5.1 WHEEL TRACK RUTTING
Wheel track rutting is the formation of longitudinal depressions in the pavement at the locations of the wheel
tracks of vehicles resulting from the compaction and shoving of the pavement laterally under repeated vehicle
traffic.
Wheel track rutting and its measurement is illustrated in Figure 2.7.5.
Severity
Light
- Rutting less than 10 mm deep.
Medium - Rutting from 10 mm to 20 mm deep.
Severe
- Rutting from 20 mm to 40 mm deep.
Very
Severe
- Rutting greater than 40 mm deep.
1-2-48
Nov. 2003 Revision
Figure 2.7.1(a)
Medium Longitudinal Crack
1-2-49
Figure 2.7.1(b)
Medium Transverse Crack
Figure 2.7.1(c)
Severe Alligator Cracks
1-2-50
Figure 2.7.1(d)
Figure 2.7.1(e)
Light Map Cracks
Medium Progressive Edge Cracks
1-2-51
Figure 2.7.2
Figure 2.7.4
1-2-52
Severe Ravelling
Severe Pothole
Figure 2.7.5
Medium Wheel Track Rutting
Figure 2.7.6
1-2-53
Severe Rippling
Figure 2.7.7
Severe Flushing
Figure 2.7.8
Slippery Surface
1-2-54
2.8
COATINGS
Coating defects are not necessarily serious in themselves; however, they are
indicative of a potential weakness in the coating and eventual loss of protection
for the surface coated. No criteria are given for the severity of material defects
in coatings, therefore, they do not need to be classified as to severity. However,
their presence and the area affected should be noted and recorded.
There are several types of material defects that commonly occur in coatings
(References 5 to 8), which can be grouped into the following three categories:
(a)
Coating Related Defects
These are defects which are related to the basic chemistry or composition of the
coating and reaction of the coating materials with each other and the environment.
Common defects of this type are:
(b)
Checking or Crazing
Cracking
Alligatoring
Chemical Attack
Chalking
Adhesion Related Defects
These are defects which are usually a result of incorrect coating selection,
contaminated substrate or improper surface preparation. Common defects of this
type are:
(c)
Undercutting
Blisters
Intercoat Delamination
Peeling
Underfilm Corrosion
Application Related Defects
These are defects which are usually a result of the improper application of the
coating. Common defects of this type are:
-
Bridging
Edge Defects
Shadows
Overspray
Pinholing
Runs
Sags
Pinpoint Rusting
1-2-55
2.8.1
COATING RELATED DEFECTS
CHECKING or CRAZING usually appears as a fine system of minute cracks in a
checkerboard pattern. This is a surface defect and does not necessarily penetrate
the full depth of the coating. They are usually inherent in the coating as some
pigments combined with some vehicles will tend to cause checking or crazing to
occur. They may also be caused by the weathering process, including wetting and
drying, heating and cooling, exposure to sunlight and contraction of the coating as
it dries or cures, Figure 2.8.1(a).
CRACKING may result from the effects of weathering or continued polymerisation of
the coating materials over time. An oxidizing or catalyzed coating applied over a
very smooth surface may crack due to shrinkage and poor adhesion to the substrate.
Cracking is an extension of the checking process and usually occurs in a linear
pattern and penetrates completely through the coating. The cracked coating tends
to spall off exposing bare substrate, Figure 2.8.1(b).
ALLIGATORING occurs if a hard, brittle or oxidizing top coat is applied over an
extensible base coat, such as an alkyd over an asphalt base.
As the surface
hardens and shrinks, very large irregular checks, usually several centimetres
across, are formed on the surface in a characteristic alligator pattern but do not
go all the way through the coating. If not over-coated with compatible material;
then, the mechanism will continue until it completely penetrates to the substrate,
Figure 2.8.1(c).
CHEMICAL ATTACK results as some coating materials may react adversely with some
air-borne chemicals and pollutants, or as a result of accidental spillage. Oil
base coatings such as alkyds are subject to damage by alkaline chemicals, Figure
2.8.1(d).
CHALKING is a surface phenomenon of some coatings that results from exposure to the
action of solar radiation and the processes of weathering over a period of time.
This results in a chalky or powdery appearance of the coating. It occurs because
many basic resins will react with sunlight and many pigments will accelerate the
process of weathering away of the resin binder between the pigment particles
leaving the pigment particles free on the surface. Chalking is usually a surface
defect and the coating is intact below the chalky surface; however, chalking can
progress and the thickness of sound coating reduced to the point where the
substrate is exposed.
2.8.2
ADHESION RELATED DEFECTS
UNDERCUTTING is the spreading of corrosion underneath the coating from a break in
the coating. It is usually caused by poor surface preparation and the application
of the coating over surfaces which contain mill scale or rust; or which have oil,
grease or dirt, and otherwise improperly cleaned surfaces. Undercutting can also
be caused by application of the coating to surfaces that are very smooth or nonporous resulting in poor adhesion of the coating. Undercutting is also promoted by
high moisture vapour permeability of the coating and penetration by oxygen and
salts, Figure 2.8.2.(a).
1-2-56
BLISTERS are dome shaped projections in paints arising from the detachment of one
coat from another or from the substrate. It is generally caused either by solvents
which are trapped within or under the paint film, or by water which is drawn
through the paint film by the osmotic forces exerted by hygroscopic salts at the
paint/substrate interface, Figure 2.8.2(b).
INTERCOAT DELAMINATION is where one coat separates from another and is usually
related to poor coating application over contaminated surfaces or to too long a
drying or curing period between coats, Figure 2.8.2(c).
PEELING is also a result of poor adhesion of the coating either from the substrate
or from a previously applied coating. It is related to the tensile strength of the
coating film itself where, if the tensile strength of the film is greater than the
adherence to the surface; then, the coating will tend to peel. Peeling between
coats is usually caused by contamination of the surface of the previous coat,
Figure 2.8.2(d).
UNDERFILM CORROSION is the building up of corrosion under the coating without the
help of a break in the coating. It is prevalent in coatings which oxidize on the
surface, such as oil base and alkyd coatings. These oxidize over time to a point
where they become porous to moisture, oxygen and chloride ions.
This coating
failure is promoted by poor surface preparation, substrate profile and surface
contamination.
2.8.3
APPLICATION RELATED DEFECTS
BRIDGING across inside corners where debris has accumulated occurs if the debris is
not properly cleaned off before the coating is applied. The coating, upon curing,
may shrink sufficiently to bridge over the area resulting in voids under the
coating.
Subsequent penetration by moisture and oxygen will result in coating
failure.
EDGE DEFECTS are a result of the improper or insufficient application of coatings
to sharp edges and corners. The coating will tend to pull away from sharp edges
and corners due to surface tension of the coating.
This results in a thinner
coating in these areas and, consequently, loss of film thickness and protection,
Figure 2.8.3.(a).
SHADOWS often result around rivets, bolts, welds, and at other areas where there
are abrupt changes in an otherwise smooth surface, and where the coating is not
applied in a sufficient number of different directions resulting in incomplete
coverage, Figure 2.8.3(b).
OVERSPRAY occurs when paint particles fall on the surface outside the normal spray
pattern. The result is a dry spray as these particles are usually dry by the time
they reach the surface. The resulting appearance is an area which is rough and dull
and does not have the same sheen as other areas where the coating is properly
applied. The dry spray will absorb solvent from the subsequent coats resulting in
poor adhesion. Overspray areas are also typically more porous and, consequently,
early coating failure can result, Figure 2.8.3(c).
1-2-57
PINHOLING can be caused by holding the spray gun too close to the surface so that
air bubbles are entrained into the coating creating voids throughout the depth of
the coating. If pinholing occurs in one coat; then, it will also tend to occur in
subsequent coats, thus providing a passage through the voids to the substrate.
Pinholing usually occurs in fast drying coatings, Figure 2.8.3.(d).
RUNS are a downward movement of a paint film in rivulets caused usually by
overthinning, slow thinners, and/or holding the spray gun too close to the
surface and depositing too much paint at one time. The perimeter of the run is
often accompanied by pinholes, Figure, 2.8.3.(e).
SAGS are heavy thicknesses of paint which have slipped and formed curtains on the
surface. They are caused by the same things that lead to runs,
Figure 2.8.3.(e).
PINPOINT RUSTING usually occurs when insufficient thickness of coating is applied
over a blast cleaned substrate.
The profile peaks lack proper protection and
continue to rust, Figure 2.8.3.(f).
1-2-58
Figure 2.8.1(a)
Checking
Figure 2.8.1(b)
Cracking
1-2-59
Figure 2.8.1(c)
Alligatoring
(typical mud crack pattern)
Figure 2.8.1(d)
1-2-60
Chemical Attack
Figure 2.8.2(a)
Figure 2.8.2(b)
1-2-61
Undercutting
Blisters
Figure 2.8.2(c)
Intercoat Delaminations
Figure 2.8.2(d)
1-2-62
Peeling
Figure 2.8.3(a)
Figure 2.8.3(b)
1-2-63
Edge Defects
Shadows
Figure 2.8.3(c)
Figure 2.8.3(d)
1-2-64
Overspraying
Pinholing
Figure 2.8.3(e)
Figure 2.8.3(f)
1-2-65
Runs and Sags
Pinpoint Rusting
2.9
REFERENCES
1. Alkali-Aggregate Reactions in Ontario, Chris Rogers, Grattan-Bellew, R, Doug Hooton, J. Ryell, and
M.D.A. Thomas, Canadian Journal of Civil Engineering, Volume 27, 2000.
2. Accelerated Corrosion in Weathering Steel Bridges, Report ME-84-03, Research Development
Branch, Ministry of Transportation and Communications.
3. Accelerated Corrosion Weathering Steel Bridges - An Update, Report ME-84-04, Research and
Development Branch, Ministry of Transportation and Communications.
4. Pavement Maintenance Guidelines:
Distresses, Maintenance Alternatives, Performance Standards. Report SP 001, Sept. 1980.
Research and Development Branch, Ministry of Transportation and Communications.
5. SSPC Painting Manual, Volume 1 (4th Edition), Good Painting Practice, SSPC the Society for
Protective Coatings, 2002.
6. SSPC Painting Manual, Volume 2 (8th Edition), Systems and Specifications, SSPC the Society for
7. SSPC-VIS 2, Standard Method for Evaluation Degree of Rusting on Painted Steel Surfaces, Standard
approved by a joint task group of members of ASTM subcommittee D01.46 and SSPC C.2, SSPC the
Society for Protective Coatings, 2000.
8. Munger, Charles C., and Vincent, Louis D., “Corrosion Prevention by Protective Coatings”, NACE
International, 1440 South Creek Drive, Houston, TX, 77084-4906.
9. Inspecting Steel Bridges for Fatigue Damage, Fisher, J.W.; Research Project No. 72-3 FHWA/PA81/005, Fritz. Lab. No. 386-15(81), March 1981.
10. Canadian Highway Bridge Design Code, CAN/CSA S6-00, Canadian Standards Association,
Toronto, Canada, 2000
11. AASHTO Guide Specifications for Fracture Critical Non-Redundant Steel Bridge Members, 1978,
and Interim 1989 revision.
12. Recommended Guidelines for Redundancy Design and Rating of Two-Girder Steel Bridges, NCHRP
Report 319, October 1989.
1-2-66
Apr. 2008
1-2-67
SECTION 3
-
STREAMS AND WATERWAYS
Contents
3.1
Streams and Waterways ........................................ 1-3-1
3.1.1 Material Defects of Streams and Waterways ............. 1-3-2
3.1.2 Performance Defects in Streams and Waterways .......... 1-3-2
3.1
STREAMS AND WATERWAYS
For the purpose of this section, a stream is defined as a body of water over or
under which a structure is built.
The defects produced in the stream by the
presence of structure components in or near the stream are detailed in this
section. Streams are to be considered as auxiliary components.
An assessment of the stream and channel stability is important for determining the
need for protective measures. A stable stream and channel is one that does not
change in size, form or location over time. They have fairly constant widths, well
protected banks and narrow sand bars.
An unstable stream and channel is one in which changes occur over time which are
large enough to become a significant factor in the maintenance of structure
components in and around the stream and channel. All alluvial channels change to
some extent over time and, therefore, have some degree of instability.
There are three principal types of streams; namely, meandering, straight and
braided.
A meandering stream is characterized by alternative S-bends which migrate laterally
downstream. Bank erosion occurs on the outside radius while deposition occurs on
the inside radius at each bend in the stream. Meandering streams may be unstable.
A straight stream is one where the length of the stream, measured down the
centreline of stream, divided by the length of the valley proper is less than 1.5.
A straight stream is usually not entirely free of meandering since the main
current often alternates from side to side.
Straight streams are usually
relatively stable.
A braided stream is identified by numerous unstable interlacing channels separated
by gravel or sand bars and small islands. Braided streams are usually highly
unstable.
The above three types of streams are illustrated in figure 3.1.
1-3-1
3.1.1
MATERIAL DEFECTS OF STREAMS AND WATERWAYS
SCOUR is the removal of material from the stream bed or bank due to the erosive
action of moving water in the stream. Scour may be general or local. General
scour is caused by the constriction to the natural flow created by the structure,
and is measured as the average depth below the original stream bed. Local scour
occurs as a result of an obstruction to the flow, such as, a pier, an abutment, the
toe of the embankment or accumulation of debris in the stream. Local scour is
measured below the level of general scour.
DEGRADATION is the lowering of the stream bed or the widening of the stream channel
due to continuous scour by the stream and usually occurring when the sediment
transport capacity of the stream is enhanced by increased flow. This often results
from a natural increase in the slope of the stream bed or as a result of artificial
alterations. Lowering of the stream bed may also result in slumping and erosion of
the stream banks, structure embankments and slope protection.
AGGRADATION is the raising of the stream bed or the narrowing of the stream channel
due to deposition of material by the stream and usually results where the sediment
transport capacity of the stream is decreased. This often results from a natural
flattening of the stream bed gradient or as a result of artificial alterations.
ICE can cause several problems, the most common of which is ice jamming at the time
of spring break-up. Ice piling against a structure may cause serious damage to the
structure and ice jams may cause severe local scour by constricting the opening at
the structure.
Jams are frequently a result of ice flows piling up against
unbroken ice at a flattening of the stream gradient. The impact of ice flows can
cause bending of exposed steel piles and the breaking of timber piles.
PIPING is the subsurface removal of fines by the movement of water through the
ground or embankments.
CHANGES IN ALIGNMENT may occur as the result of fluctuating water levels and
changes in stream velocity.
Figure 3.1.1 illustrates material defects commonly occurring in streams.
3.1.2
PERFORMANCE DEFECTS IN STREAMS AND WATERWAYS
Performance defects in streams and waterways are based upon the ability of the
structure opening to accommodate the stream flow; the frequency of flooding at the
structure; and material defects of streams that adversely affect other components
of the structure.
BLOCKAGE of the stream channel may occur as a result of accumulations of debris due
to natural causes, beavers dams, or due to aggradation of the stream bed or banks.
Large quantities of debris are carried down by relatively fast-flowing streams
having erodible banks.
1-3-2
FLOODING over the structure and adjacent roadways occurs if the opening under the
structure was not designed to accommodate the volume of water passing through it.
Flooding may also occur as a result of channel blockage.
UNDERMINING is the progression of the scour under the structure foundations.
A
A
B
B
C
Meandering
(moderately stable)
Straight
(Stable)
Section B-B
Section A-A
FIGURE 3.1
Principle Types of Streams
1-3-3
C
Braided
(unstable)
Section C-C
bank erosion, scour and ponding
borrow area
Removing large quantities of gravel
gravel from channel bottom causes
degradation upstream
A firm channel bottom or
constriction causes scour, bank
ersion and ponding downstream
ox-bow lake formed
channel
change
Channel constriction produces scour
around the bridge during flood
low water
flow
former low
water channel
high water
flow
Scour around piers is influenced by
location of pier to flow. Note change
of flow at high water
Figure 3.1.1
New channel cuts off ox-bow and steepens
channel profile with increase in flow
velocity and degradation upstream
new low
water
channel
New water channel may be
fored after a flood
Typical Material Defects in Streams (cont)
1-3-4
scour
holes
Protruding abutment produces
local scour at upstream
corner
Rip-rap around piers may cause
local scour downstream
Debris
Debris around pier reduces
opening causing increased
scour
Figure 3.1.1
Linked banks reduce scour, but
if channel is constricted it may
increase general scour at bridge
Typical Material Defects in Streams
1-3-5
1-3-6
SECTION 4
-
EMBANKMENTS AND SLOPE PROTECTIONS
Contents
4.1
Embankments ...................................................
4.1.1 Material Defects of Embankments ........................
4.1.2 Performance Defects of Embankments .....................
1-4-1
1-4-1
1-4-2
4.2
Slope Protections .............................................
4.2.1 Material Defects of Slope Protections ..................
4.2.2 Performance Defects of Slope Protections ...............
1-4-2
1-4-2
1-4-2
4.1
EMBANKMENTS
Embankments are sloped fills or cuts in the vicinity of the structure. The purpose
of the embankments is to provide for a stable change of grade between the roadway
and the surrounding ground surface, streams or other roadways under the structure.
Another purpose of the embankments is to provide support for the foundations where
they are situated within the embankments.
Embankments are normally constructed from earth, rock or a combination of these
materials. The sloping faces of embankments may be protected from the effects of
erosion or scour by slope protection systems.
Embankments are to be considered as primary components if they support the
foundation, otherwise, they are to be considered as secondary components.
4.1.1
MATERIAL DEFECTS OF EMBANKMENTS
EROSION is the gradual wearing away or removal of material by surface drainage or
wind.
Sources of surface drainage potentially leading to erosion are leakage
through expansion joints onto the embankment, runoff around the ends of wingwalls,
discharge from deck drains directly above the embankment and abutment and wingwall
subdrains discharging onto the embankment.
PIPING is the subsurface removal of fines by movement of water through the ground
or embankment.
WASHOUT is the removal of material from the ground or embankment by subsurface or
surface erosion.
SCOUR is the removal of embankment material by the action of stream flow.
1-4-1
4.1.2
PERFORMANCE DEFECTS OF EMBANKMENTS
Performance defects in embankments are related to their ability to maintain a
stable grade separation between the roadway and the surrounding terrain without
appreciable movement. Performance defects are also related to the ability of the
embankments to provide support to the foundations without appreciable movements
where the foundations are supported by the embankments.
MOVEMENT of embankments may consist of:
- settlement of embankment or roadway approaches;
- sliding of the slopes or toes of embankments;
- surface or deep seated slips.
Movement of embankments may result from:
- improper or inadequate compaction of fill;
- instability of the underlying soils;
- instability of the embankment material;
- loss of embankment material due to erosion, scour; piping, undermining,
disintegration or other causes (e.g. burrows).
UNDERMINING is the progression of scour of the embankment or the stream bed
under the embankment.
4.2
SLOPE PROTECTIONS
The purpose of the slope protections is to prevent the erosion or scour of
embankments and stream banks in the vicinity of structures. A secondary purpose is
to control the growth of grass and vegetation on steep slopes where mechanical
equipment cannot be used safely.
The types of slope protections used most commonly are summarized in Table 4.2.
4.2.1
-
MATERIAL DEFECTS OF SLOPE PROTECTIONS
Loss of slope protection material.
Disintegration or breakdown of material.
Tearing of geotextiles.
Corroded or broken wire mesh.
4.2.2
PERFORMANCE DEFECTS OF SLOPE PROTECTIONS
Performance defects in slope protections are related to their ability to protect
the embankments and stream banks from erosion or scour and are reflected in the
movements of slope protection systems.
Movements of slope protections may consist of:
- settlement of the slope protection;
- sliding of the slope protection.
1-4-2
Movements of slope protections may be caused by:
- movements of the embankments or the stream banks;
- material defects of the slope protection systems.
Type
Material Composition
Remarks
1
Organic
Grass, Brush, etc.
Used where large run-off is not
expected.
2
Rip-Rap
Stones, Rubble.
Random, hand-laid or grouted.
Commonly used in streams.
3
Granular
Crushed stone or
gravel.
Commonly used at grade
separations
4
Cast-in-Place
Concrete
Reinforced concrete
slab, 100 mm to 150 mm
thick, divided into
panels.
Commonly used at grade
separations
5
Precast
Concrete
Interlocking slabs or
elements.
Elements placed on permeable base
which permits some seepage
between elements.
6
Bituminous
Asphaltic concrete
Compacted.
7
Wire Baskets
Wire mesh baskets
filled with stones.
Commonly used near streams.
8
Bag Mortar
Premixed concrete bags
stacked on each other.
Hand placed and allowed to set in
place.
9
Geotextiles
Inorganic fabrics which
allow penetration of
water but not soil.
Normally used under other tiles
protections to prevent washing
away of fines by subgrade
seepage.
Table 4.2
Slope Protection Systems
1-4-3
1-4-4
SECTION 5
-
SUBSTRUCTURES
Contents
5.1
Substructures .................................................
5.1.1 Foundations ............................................
5.1.2 Abutments ..............................................
5.1.3 Piers ..................................................
5.1.4 Retaining Walls ........................................
1-5-1
1-5-1
1-5-2
1-5-3
1-5-3
5.2
Primary Components ............................................
5.2.1 Material Defects of Primary Components .................
5.2.2 Performance Defects of Primary Components ..............
1-5-3
1-5-4
1-5-4
5.3
Secondary Components ..........................................
5.3.1 Material Defects of Secondary Components ...............
5.3.2 Performance Defects of Secondary Components ............
1-5-4
1-5-4
1-5-4
5.1
SUBSTRUCTURES
The following components are to be considered as substructures:
-
Foundations;
Abutments and piers ;
Retaining walls;
Soil or rock under reinforced concrete box culverts or below springing lines
of soil steel structures.
5.1.1
FOUNDATIONS
Structures are normally supported on either shallow or deep foundations, based upon
the depth to rock or soils with adequate capacity to support the loads from the
structure.
(a) Shallow Foundations
Shallow foundations, footings, are used where rock or soil with
capacity is at or near the ground surface.
adequate bearing
Shallow foundations are normally made of mass concrete, reinforced concrete, wood
or masonry.
They are occasionally made of reinforced earth, gabions or cribs
filled with stones or earth.
1-5-1
Shallow foundations in soils are placed below the local frost depth at the level of
competent soil. In streams they are normally buried to protect them against scour
and may also have sheet piling as additional scour protection. Foundations on rock
do not require frost protection or scour protection.
Typical examples of shallow foundations are shown in Figure 5.1.1(a).
(b) Deep Foundations
Deep foundations, piles or caissons, are used where rock or soil, capable of
carrying the structure loads is overlain by softer material.
Commonly used piles are steel H piles, steel tube piles, timber piles, and
reinforced or prestressed concrete piles.
Caissons are normally made of large
diameter tube piles or box sections made of concrete, steel sheet piles or H piles.
They are sunk through ground or water for the purpose of placing the foundation at
the prescribed depth and, subsequently, become part of the foundation. Steel tubes
and caissons may be filled with concrete.
Piles or caissons may terminate with or without a footing, which may be located
below ground or water level. Where piles or caissons extend to the level of the
superstructure they should be inspected as piers or abutments as appropriate.
Typical examples of deep foundations are shown in Figure 5.1.1(b).
5.1.2
ABUTMENTS
Abutments consist of a number of components, each serving a specific purpose.
These components are the foundation, abutment wall, ballast wall, wingwalls and the
bearing seats.
In certain structures the abutment or some of its components may be missing, for
example:
- abutments are not present in soil steel structures or in some concrete
arches;
- in some continuous structures the end span is cantilevered out and has a
curtain wall attached to it that retains the approach fill without the need
of an abutment;
- the ballast wall and bearing seats are not needed for rigid frames, box
culverts and some concrete arches.
Abutments are commonly made of mass concrete, reinforced concrete, or wood.
Occasionally, masonry, steel piles, precast concrete, wire baskets, and reinforced
earth have been used for their construction.
Typical examples of abutments are shown in Figure 5.1.2(a). Examples of structures
without abutments are shown in Figure 5.1.2(b).
1-5-2
5.1.3
PIERS
Piers consist of a number of components, each serving a specific purpose.
These components are the foundation, pier shaft or columns, pier cap and the
bearing seats.
Piers are commonly made of reinforced concrete, steel or wood. Occasionally, mass
concrete, prestressed concrete, masonry, steel cribs, or gabions are used in their
construction.
They can be categorized as follows based on their design and
configuration.
Shafts
Bents
Columns
Trestles
Cribs
Gabions
-
concrete or masonry shafts with or without a pier cap;
concrete or steel columns with a pier cap;
single or multiple columns without a pier cap;
braced wood or steel columns with a pier cap;
wood or steel cribs, empty or filled with stone or earth
wire baskets filled with stones.
Typical examples of piers are shown in Figure 5.1.3.
5.1.4
RETAINING WALLS
Retaining walls consist of walls with or without foundations.
Retaining walls are commonly made of mass concrete, reinforced concrete, wood.
Occasionally, masonry, steel piles, precast concrete, wire baskets, bag mortar and
reinforced earth have been used for their construction. They can be categorized as
follows based on their design:
Gravity Retaining - mass concrete, masonry, timber cribs, concrete cribs, steel
Walls
cribs, wire baskets and bag mortar.
Cantilever
Retaining Walls
- reinforced concrete, steel sheet piling, post and lagging
(concrete, wood or steel or a combination of these).
Anchored
Retaining Walls
- Reinforced earth and tie-back walls.
Typical examples of gravity, cantilevered and anchored retaining walls are
shown in Figures 5.1.4(a), (b) and (c) respectively.
5.2
PRIMARY COMPONENTS
Foundations, abutment walls and piers are to be considered as primary
components.
1-5-3
5.2.1
MATERIAL DEFECTS OF PRIMARY COMPONENTS
Material defects are as given in Section 2.
5.2.2
PERFORMANCE DEFECTS OF PRIMARY COMPONENTS
Performance defects of foundations relate to their ability to support the
components above them and to transmit the loads imposed on them to the rock or soil
without appreciable movements.
Performance defects of abutment walls relate to their ability to provide adequate
support to the superstructure and to retain the approach fills without appreciable
movements.
Performance defects of piers relate to their ability to provide adequate support to
the superstructure without appreciable movements.
Movements of foundations, abutment walls and piers may consist of vertical,
longitudinal or transverse translations or rotations.
Some of the common causes
for these movements are:
-
material defects leading to loss of strength of components;
overloading from the superstructure;
excessive earth pressures;
excessive ice pressure;
consolidation or failure of the soil;
scour or erosion of the soil below the foundations;
frost action.
It is important to determine if the component is stable or unstable as indicated by
the rate of increase of movement.
5.3
SECONDARY COMPONENTS
Ballast walls, wingwalls, retaining walls and bearing seats are to be considered as
secondary components. The foundations of wingwalls and retaining walls are also to
be considered as secondary components.
5.3.1
MATERIAL DEFECTS OF SECONDARY COMPONENTS
5.3.2
PERFORMANCE DEFECTS OF SECONDARY COMPONENTS
Performance defects of bearing seats relate to their ability to provide adequate
support to the bearings and, as such, are based on the loss of competent bearing
area of the bearing seats.
1-5-4
Performance defects of ballast walls, wingwalls and retaining walls relate to their
ability to retain the fill behind them without appreciable movements. Movements of
the walls may consist of vertical, longitudinal or transverse translations or
rotations. Some of the common causes for these movements are:
-
material defects leading to loss of strength of the walls;
overloading from the superstructure;
excessive earth pressures;
excessive ice pressure;
failure of the soil or foundation;
scour or erosion of the soil below the footings;
frost action.
It is important to determine if the walls are stable or unstable as indicated by
the rate of increase of the movements.
1-5-5
Abutment Wall,
Wingwall
Retaining Wall
or Pier
Footing
Multi - columns
Single
Column
Footing
Footing
Rigid Frame or Open Footing Culvert
Concrete Arch or
Soil - steel Structure
Footing
Footing
CONCRETE SPREAD FOOTINGS
Figure 5.1.1(a) Typical Shallow Foundations
1-5-6
ABUTMENT WALL
WINGWALL
RETAINING WALL
OR PIER
FOOTING
MASONRY FOOTING
ABUTMENT WALL
WINGWALL
RETAINING WALL
OR PIER
FOOTING
WOOD CRIB FOOTING
NO
FOOTING
NO
FOOTING
SOIL ACTING AS
FOUNDATION
SOIL STEEL STRUCTURE
SOIL ACTING AS
FOUNDATION
BOX CULVERTS
Figure 5.1.1(a) Typical Shallow Foundations (Continued)
1-5-7
CROSS
BRACING
PIER CAP
FOOTING
ABUTMENT WALL
WINGWALL
RETAINING WALL
OR PIER
WOOD OR STEEL PILES
PIER TRESTLE
PILES OR CAISSONS
PILES TERMINATING IN FOOTING
PIER CAP
ABUTMENT WALL
WINGWALL OR
RETAINING WALL
PILES OR CAISSONS
PIER BENT
WOOD OR STEEL PILES
PILES AND LAGGING
ABUTMENT
OR PIER
ABUTMENT
OR PIER
MULTIPLE CELL CAISSONS
SINGLE CELL CAISSON
Figure 5.1.1(b) Typical Deep Foundations
1-5-8
TYPICAL ABUTMENT
COMPONENTS
BALLAST
WALL
BEARING
SEAT
WINGWALL
~
BEARING
SEAT
WINGWALL
BEARING
SEAT
ABUTMENT
WALL
ABUTMENT
WALL
FOUNDATION
REINFORCED CONCRETE
CLOSED ABUTMENT
BALLAST
WALL
BALLAST
WALL
FOUNDATION
WINGWALL
REINFORCED CONCRETE
SPILL THROUGH ABUTMENT
WOOD OR
STEEL PILES
WOOD LAGGING
FOOTING
WOOD CRIB ABUTMENT
PILE AND LAGGING ABUTMENT
BEARING
SEAT
WINGWALL
BALLAST WALL
~
LEG
~
ABUTMENT
WALL
FOUNDATION
RIGID FRAME OR OPEN
FOOTING CULVERT
FOOTING
STONE MASONRY ABUTMENT
Figure 5.1.2(a) Typical Abutment Components
1-5-9
End Diaphragm
Piers
No Abutment
No Abutment
CANTILEVERED END SPANS
BOX CULVERTS
Footings
No Abutment
No Abutment
CONC. OR SOIL STEEL STRUCTURE
SOIL STEEL STRUCRURE
Figure 5.1.2(b) Structures Without Abutments
1-5-10
PIER CAP
PIER CAP
STEEL OR
REINFORCED
CONCRETE
COLUMNS
~
REINFORCED
CONCRETE
OR MASONERY
FOUNDATION
FOUNDATION
PIER BENT
PIER SHAFT
PIER CAP
REINFORCED
CONCRETE
COLUMNS
STEEL OR
REINFORCED
CONCRETE
COLUMNS
FOUNDATION
FOUNDATION
INCLINED LEG BENT
SINGLE COLUMN
PIER CAP
REINFORCED
CONCRETE
COLUMNS
FOUNDATION
MULTIPLE COLUMN
WOOD OR STEEL TRESTLE
Figure 5.1.3 Typical Piers
1-5-11
~
~
REINFORCED CONCRETE
WOOD OR STEEL
FOUNDATION
GABIONS
CRIBS
Figure 5.1.3 Typical Piers (continued)
1-5-12
WIRE MESH
STONE FILL
GRADE
GRADE
MASS
CONCRETE
GRADE
PRECAST
ELEMENTS
GRADE
FOUNDATION
PRECAST CONC. DRY WALL
MASS CONCRETE
PRECAST
ELEMENTS
GRADE
GRADE
STONE
OR BRICKS
GRADE
GRADE
MASONRY
PRECAST CONCRETE CRIBS
GRADE
~
STEEL
ELEMENTS
~
~
GRADE
GRADE
STONE FILL
GRADE
METAL CRIBS
Figure 5.1.4(a)
WIRE MESH
GABIONS
Typical Gravity Retaining Walls
1-5-13
GRADE
WOOD
ELEMENTS
WOOD
ELEMENTS
TIE
RODS
TIE
RODS
GRADE
GRADE
ROCK FILL
WOOD DRY WALL
WOOD CRIB
GRADE
BAG OF
MORTAR
GRADE
BAG MORTAR
Figure 5.1.4(a)
GRADE
Typical Gravity Retaining Walls (Continued)
1-5-14
GRADE
GRADE
GRADE
REINFORCED
CONCRETE
GRADE
FOUNDATION
REINFORCED CONCRETE
SHEET PILES
GRADE
GRADE
BUTTRESS
COUNTERFORT
REINF.
CONCRETE
GRADE
GRADE
REINFORCED CONCRETE
COUNTERFORT WALL
REINFORCED CONCRETE
BUTTRESS WALL
GRADE
GRADE
WOOD
PILE
STEEL PILE
GRADE
GRADE
LAGGING PLACED
BETWEEN PILES
LAGGING PLACED
BETWEEN PILES
STEEL PILES AND LAGGING
STEEL PILES AND LAGGING
Figure 5.1.4(b)
WOOD
LAGGING
Typical Cantilever Retaining Walls
1-5-15
GRADE
GRADE
PRECAST
CONCRETE
PANELS
WALER
CABLE TIE BACK
SHEET
PILING
GRADE
DEAD MAN
ANCHOR
GRADE
FOOTING
REINFORCING
STRIPS
TIE - BACK
REINFORCED EARTH
Figure 5.1.4(c)
Typical Anchored Retaining Walls
1-5-16
SECTION 6
-
BEARINGS
Contents
6.1
Bearings ........................................................ 1-6-1
6.1.1
Material Defects of Bearings ............................ 1-6-3
6.1.2
Performance Defects of Bearings ......................... 1-6-3
6.1
BEARINGS
Bearings are normally located at the interface between the superstructure and
substructure.
In the case of suspended spans, they are located between the
suspended span and the supporting superstructure. Bearings are not needed in some
structures, for example, culverts and rigid frames. Bearings are not used in short
span structures where the superstructure rests directly on the substructure.
Bearings are to be considered as secondary components except for the pin and hanger
bearing which is to be considered as a primary component.
There are numerous types of bearings made of various materials that have been used
in bridges over the years. Bearings usually consist of a number of parts which may
include the following, but not all bearings would have these and some may have
other parts as well.
-
a levelling pad;
a base plate sitting on the levelling pad;
anchor bolts or pins to secure the base plate to the supports;
the bearing itself;
retainer bars or pins to prevent transverse movement of the bearing;
a shoe plate attached to the underside of the superstructure.
Materials used in bearings are steel, rubber, neoprene, polymers, aluminum or a
combination of these. In the past, lead, copper, bronze or iron were also used.
Bearings are subdivided into two main categories, fixed or expansion bearings,
based on their capability for movement.
Fixed bearings do not allow for
translation but may allow rotation. Expansion bearings allow for translation and
may also allow rotation.
Bearings are grouped as follows and are illustrated in Figure 6.1(a) to 6.1(g).
1-6-1
(a)
Steel Plate Bearings
Steel plate bearings may be used with or without translational and rotational
capabilities depending on the number of parts provided.
Fixity of base plate is provided by anchor bolts or pins;
Translation is provided by steel plate sliding on concrete, bronze, copper or lead
or by stainless steel plate sliding on a tetraflouraethylene(TFE) polymer;
Rotation is provided
polyurethane.
(b)
by
a
compressible
material,
usually
elastomeric
or
Elastomeric Bearings
Elastomeric bearings provide translation and rotation as a function of their
stiffness. Thin pads up to 25 mm thick act as fixed bearings. Thicker pads act as
expansion bearings and are often reinforced with steel or aluminum plates.
Fixity is provided by pins or anchor bolts;
Translation is provided by the pad;
Rotation is provided by compression of the pad.
(c)
Pot and Disc Bearings
Pot and disc bearings provide rotation.
They may also provide translation.
Fixity is provided by anchor bolts or pins;
Translation is provided by the sliding of a stainless steel surface on a TFE
surface;
Rotation is provided by compression of a confined elastomer or polymer disc.
(d)
Spherical and Cylindrical Bearings
Spherical and cylindrical bearings provide rotation. They may also provide
translation. Cylindrical bearings rotate about the axis of the cylinder, while
spherical bearings can rotate about any axis. A TFE sheet is often bonded to the
lower surface.
Translation is provided by sliding of a stainless steel surface on a TFE surface;
Rotation is provided by the sliding of one curved surface over another.
(e)
Rocker Bearings
Rocker bearings provide both translation and rotation.
Translation is provided by tilting or rotation of the rocker;
Rotation is provided by curved top or bottom surfaces.
1-6-2
(f)
Roller Bearings
Roller bearings provide translation.
They may also provide rotation.
Translation is provided by rolling of the rollers on the base plate;
Rotation for single rollers is provided by the curved surface of the roller. For
multiple rollers, rotation is provided by a pin connection or curved surface in
plate above the roller nest.
(g)
Pin and Hanger Bearings
Pin and hanger bearings provide both translation and rotation.
Translation is provided by movement of the hangers about pins in suspended and
cantilevered girders;
Rotation is provided by rotation about the pins.
6.1.1
MATERIAL DEFECTS OF BEARINGS
Material defects in bearings, in addition to those given in Section 2, are:
-
lack of lubrication where required;
cracked or broken parts or plates;
loose or missing assembly pins, bolts or nuts;
bent, loose or missing anchor bolts or pins;
worn pins, rollers, rockers or rolling surfaces;
electrolytic corrosion of dissimilar materials in contact,
such as, steel and aluminum or steel and bronze;
cracks, splits or tears in elastomeric pads;
elastomer leaking out of pots in pot bearings;
scored TFE surfaces;
scratched or damaged stainless steel surfaces;
pulled out sliding plates.
6.1.2
PERFORMANCE DEFECTS OF BEARINGS
The performance of the bearing is based upon its ability to support and transfer
loads from the superstructure to the supports; and, to allow for or restrict
translational or rotational movement of the superstructure at the bearing location.
The proper functioning of the bearing is vital to the performance of the structure
as malfunction of the bearings may introduce detrimental stresses into other
structure components.
1-6-3
The performance of the bearing as regards movement is based upon either the
restriction of movement for expansion bearing or the movement of fixed bearing;
and, insufficient reserve for anticipated further movement of expansion bearings.
The amount of movement that a structure, and therefore the bearing, may be subject
to is a function of the superstructure material, type of construction, expansion
length from point of fixity and surrounding air temperature.
The amount of movement that a bearing can accommodate is a function of the type of
bearing and the air temperature at the time the bearing was installed.
It may not be possible to exactly determine the expected movements that a bearing
may be subject to or the reserve capacity of the bearing as; the bearing may have
been subjected to unaccounted movements; such as, movement of the abutment wall;
and, the bearing may have been jacked up and relieved of movement during its
lifetime.
The performance of bearings as regards load capacity and transfer is based upon the
uniform contact of the bearing with the superstructure and substructure over the
bearing surfaces; and, the ability of the bearing to carry the load without
distress.
1-6-4
SLIDING
MATERIAL
BEAM
SHOE
PLATE
ANCHOR
BOLT
LOWER
PLATE
COMPRESSIBLE
MATERIAL
LEVELLING
PAD
Figure 6.1(a)- Steel Plate Bearing
ELASTOMETER
STEEL PLATES
~
LEVELING PAD
PINTLE
Figure 6.1(b) - Elastomeric Bearing
anchor
studs
STAINLESS STEEL
ANCHOR
STUDS
SHOE
PLATE
shoe
plate
T.F.E.
THRUST
PLATE
~
POT
LEVELLING
PAD
stainless
steel
T.F.E.
T.F.E.
CONFINED
ELASTOMER
base plate
confined
compressible
pintle
disk
Multi-Directional Disk Bearing
PISTON
PINTLE
Expansion Pot Bearing
Figure 6.1(c) Figure 6.1
Pot or Disc Bearing
Typical Types of Bearings
1-6-5
ANCHOR STUDS
T.F.S.
SHOE PLATE
STAINLESS
STEEL
ELASTOMER
LEVELLING
PAD
ANCHOR BOLTS
Figure 6.1(d) - Spherical Bearing
SHOE PLATE
pin
wing plate
ELASTOMERIC
ENCAPSULATION
shoe
plate
rocher
base
plate
BASE
PLATE
LEVELLING PAD
Rocker Bearing
Steel Rocker Bearing
Figure 6.1(e) - Steel Rocker Bearing
GIRDER
~
SHOE PLATE
ROLLER
LEVELLING
PAD
BASE PLATE
Figure 6.1(f) - Expansion Roller Bearing
Figure 6.1
Typical Types of Bearings (cont'd)
1-6-6
STEEL PIN
STEEL HANGER
WINDLOCK
SUSPENDED
GIRDER
CANTILEVER STEEL
GIRDER
Figure 6.1(g) - Pin and Hanger Bearing
Figure 6.1
Typical Types of Bearings (cont'd)
1-6-7
1-6-8
SECTION 7
-
JOINTS
Contents
7.1
Joints ........................................................ 1-7-1
7.1.1 Material Defects Of Joints ............................. 1-7-3
7.1.2 Performance Defection Of Joints ........................ 1-7-3
7.1
JOINTS
Joints in decks may occur between the deck and the abutment, over the piers between
adjacent spans, or within the span at suspended spans.
Joints consist of the following parts, all of which may not be present at each
joint.
- A gap to allow for movement;
- Armourings and anchorages on each side of the gap to protect the edges of
the gap;
- Seals or sealants in the gap to prevent water from leaking through the gap;
- A trough under an open gap to catch drainage and dispose of it away from
components under the gap.
Joints can be divided into open joints which permit the free flow of water and
debris, and sealed joints which prevent the flow of water and debris through the
joint. Joints can also be divided into expansion joints which accommodate
longitudinal, transverse, vertical and rotational movements and fixed joints which
accommodate rotational movements only.
Types of joints commonly used in structures are described below and illustrated in
Figures 7.1(a) to 7.1(f).
(a) Open Joints
Open joints consist of an open gap whose edges may be protected by armouring;
Sliding plate joints have a flat steel plate bridging the gap of an open joint.
The steel plate is welded to one armouring and free to slide over the top surface
of the other armouring.
Finger plate joints have two steel plates cut and arranged to form a series of
intermeshing 'fingers' which are secured to anchorages on each side of the joint
and cantilever over the open gap.
Drop-in-T joints have a "T" section bridging the open gap and supported on the
armouring on each side of the joint.
1-7-1
(b) Poured-In-Place Joints
Paved-over-joints consist of any joint that has been paved over with asphalt
pavement. To prevent random cracking of the asphalt pavement over the joint a
groove is sometimes cut or formed in the pavement and filled with a sealant.
Hot or cold poured bituminous or mastic asphalt joints consist of an inert filler
placed in the joint gap to below the level of the finished grade, and a hot or cold
poured bituminous or mastic asphalt sealant filling the remaining gap to the
finished grade. It may be used with asphalt or concrete pavements.
Cold poured polyurethane joints consist of a formed groove in a concrete pavement
which is filled with a cold poured polyurethane compound. This material is not
used with asphalt pavements because of incompatibility between the bituminous and
polyurethane materials.
Hot poured mastic asphalt systems consist of a plug seal placed in the joint gap
and an adhesive waterproof membrane hot poured over the joint for a distance of
about 450 mm on each side of the gap. Alternating layers of hot poured mastic
asphalt and reinforcing mesh are then placed over the joint up to the level of the
adjacent asphalt or concrete pavement. Additional hot poured rubberized material
is also sometimes poured into grooves cut over the joint and between the mastic
asphalt and adjacent roadway surface.
(c) Compression Seal Joints
Elastomeric seal joints consist of a precompressed extruded elastomeric seal bonded
to the sides of the joint gap whose edges may be protected by armouring.
Ethylene vinyl acetate joints consist of a precompressed ethylene vinyl seal (looks
like foam) bonded to the sides of the joint gap whose edges may be protected by
armourings.
These joints allow for movements by changes in the amount of the precompression of
the seal.
(d) Elastomeric Cushion Joints
Elastomeric cushion joints consist of a moulded steel reinforced elastomeric
assembly that spans over the gap. These joints allow for movements by deformation
of the moulding.
(e) Multiple Seal (Modular) Joints
Multiple seal (modular) joints consist of two or more elastomeric seals placed
between three or more steel separation beams which are placed on steel support
beams spanning across the joint gap. These joints are used where large movements
are required.
1-7-2
(f) Strip Seal Joints
Strip seal joints consist of an elastomeric seal that is held in place by one of
the following methods:
-
press fitted into preformed armourings;
vertically bolted down with steel plate hold downs;
vertically bolted down and the seal is integral with elastomeric armourings;
horizontally bolted in and has steel armourings;
clamping devices with stop bars.
These joints allow for movement by the flexing of the elastomeric seal.
7.1.1
MATERIAL DEFECTS OF JOINTS
Material defects of joints in addition to those given in Section 2 are:
-
corrosion and delamination of steel components;
pulling away or popping out of the seal or sealant;
cracks, splits, tears or holes in the seal or sealant;
loose or missing sections of the seal or sealant;
abrasion, wear or aging of the seal or sealant;
compression set or loss of resiliency of the seal or sealant;
loss of bond between the seal or sealant and the adjacent pavement;
shrinking away of the sealant from the adjacent pavement;
loose, broken or missing bolts, nuts, washers or other anchorage devices;
loose, bent, cracked, broken, missing or damaged finger plates, sliding
plates, extrusions, support components or armourings;
cracking of welds and welded connections;
cracking, spalling or breaking up of the concrete, asphalt, or other
material adjacent to the joint;
softening or shifting of mastic asphaltic materials.
7.1.2
PERFORMANCE DEFECTS OF JOINTS
The performance condition rating of joints is based upon their ability to:
- accommodate the movements of the superstructure;
- prevent the leakage of roadway drainage through the joint in the case of
sealed joints;
- maintain the continuity of the roadway surface and support wheel loads.
The performance of joints as regards movement is based upon the restriction to
movement and evidence of insufficient reserve for anticipated further movement.
The amount of movement that a structure and, therefore, joint may be subject to is
a function of the superstructure material, type of construction, expansion length
from point of fixity and surrounding air temperature.
1-7-3
The amount of movement that a joint can accommodate is a function of the type of
joint, and the air temperature and joint gap set at the time of installation.
It may not be readily possible to determine the exact amount of movement that a
joint may be subject to or the capacity of the joint for movement as complete
information on structure movements and joint capacity is often not directly
available at the time of inspection. However, the relative size of the joint gap
can be assessed with respect to the expansion length from point of fixity and air
temperature at the time of inspection.
An incorrect joint gap is likely a symptom of improper functioning of the bearings,
or of movements of the abutments, pier or foundation. The inspector shall measure
and record the joint gap and air temperature at the time of inspection.
The performance of joints as regards roadway continuity is based upon the adverse
effects that the misalignment of the joint components on either side of the joint
may present to traffic.
Vertical misalignment can result in a bumpy ride across the joint and a potential
hazard of loss of vehicle control. Vertically misaligned joints are also subject
to damage by snow-plows.
Horizontal misalignment can result in binding or jamming of the joint and tearing
of the joint seal or sealant.
The performance of joints as regards watertightness, in the case of sealed joints,
is based upon the extent of leakage of roadway drainage through the joint. Joint
leakage can result in serious deterioration of the joint materials and other
structure components located below the joint.
1-7-4
Armouring
(Typ.)
Sliding
Plate
Anchorage
(Typ.)
Sliding Plate Joint
Open Gap Joint
Finger
Plates
T Section
Finger Plate Joint
Drop-in-T Joint
Figure 7.1(a) Open Joints
1-7-5
Figure 7.1(b) Poured-In-Place Joints
1-7-6
Apr. 2008
Precompressed
Elastomeric
Extrusion
Precompressed Ethylene
Vinyl Acetate
Armouring
(typ.)
Bonding Agent
Anchorage
(typ.)
Steel Retaining
Bars
Bonding
Agent
Figure 7.1(c)
Compression Seal Joints
Steel Reinforcing Plate
Sealant
Elastomeric Cushion
Anchorage
Compressed
Sealant
Figure 7.1(d)
Elastomeric Cushion Joints
Separation
Beams
Seals
Support Beams
Figure 7.1(e)
1-7-7
Multi-Seal Joints
Preformed
Retainer
Seal
Seal
Anchor
Strip Seal in Preformed Retainer
Elastomeric
Armouring
Preformed
Retainer
Elastomeric
Concrete
Strip Seal in Elastomeric Concerte
Seal
Strip Seal - Integral With
Elastomeric Armouring
Steel
Plate
Seal
Strip Seal Vertically Bolted Down
Stop
Bar
Seal
Seal
Bolts
Strip Seal Horizontally Bolted
Clamping
Device
Strip Seal in Clamping Devices
Figure 7.1(f) Strip Seal Joints
1-7-8
SECTION 8
-
SUPERSTRUCTURES
Contents
8.1
Superstructures ...............................................
8.1.1 Beams and Girders ......................................
8.1.2 Thick Slabs ............................................
8.1.3 Trusses ................................................
8.1.4 Arches .................................................
8.1.5 Culverts, Tunnels and Soil-Steel Structures ............
8.1.6 Diaphragms .............................................
8.1.7 Sway Bracings ..........................................
8.1.8 Lateral Bracings .......................................
1-8-1
1-8-2
1-8-2
1-8-3
1-8-4
1-8-5
1-8-6
1-8-6
1-8-7
8.2
Primary Components ............................................ 1-8-7
8.2.1 Material Defects of Primary Components ................. 1-8-7
8.2.2 Performance Defects of Primary Components .............. 1-8-7
8.3
Secondary Components .......................................... 1-8-8
8.3.1 Material Defects of Secondary Components ............... 1-8-8
8.3.2 Performance Defects of Secondary Components ............ 1-8-8
8.4
References
8.1
SUPERSTRUCTURES
.................................................... 1-8-8
Superstructures normally consist of all components of structures supported on the
substructures. The following components of superstructures are covered in this
section:
-
Beams and girders;
Thick slabs;
Trusses;
Arches;
Culverts;
Soil Steel Structures;
Movable bridges in fixed position;
Suspension bridges;
Stringers and floor beams under the decks;
Diaphragms;
Sway bracings;
Lateral bracings;
Other parts of the superstructure, such as, decks, curbs, sidewalks, parapet walls,
railings and expansion joints are covered in other sections of OSIM.
Movable bridges shall be inspected and recorded by the type of the main load
carrying components.
Inspection of mechanical or electrical parts of movable
bridges is not covered in OSIM.
1-8-1
8.1.1
BEAMS AND GIRDERS
Beams and girders are made of reinforced or prestressed concrete, steel or wood.
Beams and girders may be simply supported, semi-continuous for live and
superimposed dead loads, continuous over a number of spans or cantilevered beyond
the support with a drop-in section added to complete the span.
Concrete beams or girders are cast-in-place or precast as one unit or in segments.
They may be T-shape, rectangular or trapezoidal in shape and may have single or
multiple voids of various shapes in them.
Steel beams or girders are rolled into standard shapes or built-up into I-shape,
rectangular or trapezoidal boxes by riveting, bolting or welding. They may be
unstiffened or stiffened with vertical or longitudinal stiffeners. They may be
erected as single units or in segments.
Wood beams or girders may be sawn, laminated or glued and are, normally,
rectangular in shape.
They are erected as single units but may sometimes be
spliced together with steel plates, fasteners or gang-nail plates.
Beams and girders support decks directly on them except in the case of half-through
girders in which the load from the deck is first transferred to stringers and floor
beams and then to the girders.
Beams and girders may have diaphragms and lateral bracings between them. Concrete
girders, normally, have solid concrete diaphragms whereas steel girders may have
diaphragms made of steel beams, girders, channels or angles. Steel girders may
also have lateral bracings made of steel angles or channels.
Beams and girders carry loads by flexural, shear or torsional resistance. Examples
of typical beams and girders are illustrated in Figure 8.1.1.
8.1.2
THICK SLABS
Thick slabs are made of reinforced or prestressed concrete or a combination of
these.
They may be simply supported or continuous.
They may be solid or contain round, rectangular or trapezoidal voids, and are
normally cast-in-place. The deck slabs of rigid frames are to be considered as
thick slabs.
The top surface of thick slabs acts as the deck and shall be inspected as detailed
in Section 9.
Thick slabs carry loads by flexural, shear, torsion and axial forces depending on
the fixity and configuration of the support systems. Examples of thick slabs used
are illustrated in Figure 8.1.2.
1-8-2
8.1.3
TRUSSES
Trusses are made of steel or wood.
existence.
A few trusses made of cast iron are still in
Trusses may be single or multiple span and may be simply supported or continuous.
They may also be cantilevered beyond the support with a 'drop-in' truss section to
complete the span.
Trusses consist of top and bottom chords, verticals and diagonals.
Types of trusses commonly encountered are the through truss, half-through (pony)
truss, deck truss and the bailey bridge truss.
Through trusses are connected together across the top chords above the roadway
level by transverse portals, sway frames and lateral bracings. The bottom chords
are connected together below the roadway level by transverse floor beams which
support longitudinal stringers and the deck. The bottom chords are also connected
by lateral bracings below the deck.
Half-through trusses are not connected across the top chords allowing for
unrestricted overhead clearance. Sway braces or rakers are connected between the
top chords and floor beams, or needle beams, to provide lateral restraint to the
top chord. The bottom chords are connected together below the roadway level by
transverse floor beams which support longitudinal stringers and the deck.
The
bottom chords are also connected by lateral bracings below the deck.
Deck trusses are located entirely below the roadway level. They may directly
support the deck, or the deck may be supported on longitudinal stringers and
transverse floor beams resting on the deck trusses. Adjacent trusses are also
commonly connected by transverse cross bracing between the top and bottom chords,
and by additional lateral bracing between the bottom chords.
Bailey bridge trusses are built of components that can be erected into a number of
different types of trusses. The most common being the half-through type. Sway
bracings, lateral bracings and floor systems for the bailey bridges are similar to
the half-through trusses described above.
Components of steel trusses consist of individual rolled sections or are built-up
by bolting, riveting or welding several sections together. Older steel trusses may
contain solid round or square bars or eye-bars, while more recent steel trusses may
also contain tubular sections. Components of wood trusses are typically made from
solid rough-sawn sections or are built-up by bolting or gluing several sections
together. Steel rods are also often used for tension components in wood trusses.
Individual truss components are connected together at joints with splice plates or
gusset plates fastened by pins, rivets, bolts, lag-screws, nails or by welding.
While their overall configuration may vary, trusses are built up of individual
components interconnected in triangular arrangements in such a manner that the
components resist applied loads axially, through compression or tension.
1-8-3
However, depending on the degree of fixity, either actual or assumed, at the
connections, and on the location of the applied load on the member, some of the
truss components may also be subject to flexural, shear or torsional loads. Trusses
and common terminology used to describe their components are illustrated in Figure
8.1.3(a).
Typical bailey bridge configurations and components are shown in Figures 8.1.3(b)
and (c). For a complete coverage of bailey bridges see reference (1).
8.1.4
ARCHES
Arches are made of concrete, steel, wood or masonry.
Arches may be single or multiple span and may be hinged or fixed at the supports.
They may have an intermediate hinge at their crown.
Arches consist of arch ribs, top or bottom chords, verticals and diagonals.
Types of arches commonly encountered are the tied (bowstring) arch, through arch,
open spandrel arch, filled spandrel arch and barrel arch.
Tied (Bowstring) arches are used where the soil is not capable of resisting the
horizontal thrust of the arch rib. The bottom chord, or tie, may also support the
deck system as they are usually at the same level. There may also be a system of
portal or sway frames and lateral bracing between the arch ribs over the roadway.
In steel tied arches there may also be a system of lateral bracing under the deck.
Through arches are used where the soil is capable of resisting the horizontal
thrust of the arch. In this arch, the deck and floor system is suspended from the
arch rib by hangers. The arch ribs are also connected together across the top by a
system of portal and sway frames and lateral bracing. There may also be a system
of lateral bracing under the deck.
Open spandrel arches are used where the soil is capable of resisting the arch
thrust. In this type of arch the deck is located above the level of the arch
crown, and the deck and floor system is supported on columns carried down to the
arch rib(s).
In steel spandrel arches there are two or more parallel ribs interconnected by a
bracing system. Concrete spandrel arches may have several ribs interconnected with
diaphragms, but are also commonly built with only one solid arch, the full width of
the deck.
Filled spandrel arches are commonly used for short spans, and is usually fixed
ended. The arch is backfilled with earth, granular or other suitable fill which
forms the base for the deck. The sides of this arch are closed by retaining walls
and wingwalls.
Barrel arches are similar to the filled spandrel arches except that the sides are
open and therefore there are no retaining walls.
1-8-4
Components of steel arches consist of individual rolled sections or are built-up by
bolting, riveting or welding several sections together. Older steel arches may
contain solid round or square bars or eye-bars, while more recent steel arches may
also contain tubular sections.
In steel arches, the components are connected together at joints with splice plates
or gusset plates fastened by pins, rivets, bolts or by welding. In comparison,
concrete arches are usually constructed monolithically with the deck system, ties,
railings, hangers, and arch rib rigidly connected so that interaction and stress
distribution among the components is extremely complex.
While their overall configuration may vary, the arrangement and connection of their
components and the degree of fixity at the supports and between the connections
determine the distribution of applied loads internally in the arch and the transfer
of load to the foundation or soil. The arch ribs resist applied loads mainly by
compression and flexure. The arch ties resist loads mainly by tension and some
flexure depending on the location of the applied loads.
Concrete arches are usually monolithically cast, with the result that the
interaction and stress distribution among the components is extremely complex.
Also, when the arches have fixed ends they are very sensitive to differential
settlement or rotation of the foundation, which may produce overstressing and
cracking locally.
Arches and the common terminology used to describe them are illustrated in Figures
8.1.4.
8.1.5
CULVERTS, TUNNELS AND SOIL-STEEL STRUCTURES
Culverts and soil-steel structures are bridges embedded in fill. In most cases,
they convey water through an embankment; however, occasionally they provide access
to pedestrian, rail or vehicular traffic through the embankment.
A tunnel is a bridge constructed through existing ground.
In most cases it
provides access to pedestrian, rail or vehicular traffic.
Occasionally, it is
designed to convey water.
Culverts and tunnels may be made of concrete or wood. Soil- steel structures are
comprised of corrugated steel pipe or plates, and soil, designed and constructed to
induce a beneficial action between the structure and the soil.
Soil-steel
structures are constructed in several shapes; namely, round, ellipses, pipe arches,
superspans and with or without ears or relieving slab.
High embankments or fills may impose very large vertical and lateral earth loads on
culverts and tunnels which can result in structural failure of the roof, floor slab
or walls.
The strength of a soil-steel structure is derived from the interaction between the
structure and the surrounding soil. Vertical loads from the overlying soil and
traffic are transmitted by arching action to the underlying soil. If the side
support is not provided due to inadequate placement, compaction or loss of soil or
backfill material; then, failure of the structure can result.
1-8-5
Culverts, tunnels and soil-steel structures are divided into two main types
according to cross-section; namely, open invert and closed invert. An open invert
structure has a floor of natural soil, bedrock or other material that is not
structurally integral with the walls. A closed invert structure is one where the
floor is structurally integral with the walls.
Where these structures are used to carry water their basic components can be
divided into inlet, barrel and outlet as shown in Figure 8.1.5(a).
The inlet
channels water into the barrel and the outlet channels the water back into the
stream.
The inlet and the outlet may also contain headwalls, cut-off walls,
wingwalls, headerwalls and aprons to provide protection against scour and piping.
The barrel and outlet may also contain drop-outlets, stilling basins, chutes and
stepped flumes to dissipate the energy of the water before it re-enters the stream,
as shown in Figure 8.1.5(b).
When a roadway is widened or when the road grade is raised, extensions to these
structures may be built using different materials. It is necessary to inspect the
full length of these structures.
Typical examples of culverts, tunnels and soil-steel structures are illustrated in
Figure 8.1.5(c).
8.1.6
DIAPHRAGMS
Diaphragms are made of steel, wood or concrete components.
Diaphragms span between the primary load carrying components such as beams,
girders, deck trusses or are located inside box sections.
They are normally
located in the vertical plane.
Diaphragms may be solid, or built up from individual steel or wood sections which
are assembled together to form x-frames or k-frames using rivets, bolts, nails or
by welding.
Diaphragms can be distinguished as load bearing or non-load bearing. Load bearing
diaphragms directly support superstructure reactions or are designed for jacking
purposes. Non-load bearing diaphragms provide lateral support or restraint to other
superstructure components.
Typical diaphragms are illustrated in Figure 8.1.6.
8.1.7
SWAY BRACINGS
Sway bracings are made of concrete, steel or wood.
Sway bracings are the transverse bracings between primary components and are
normally located in the vertical plane. In the case of half-through trusses the
sway bracings are attached to the outside of each truss instead of between the
trusses.
1-8-6
Sway bracings may be solid, or built up from individual steel or wood sections
which are assembled together to form x-frames or k-frames using rivets, bolts,
nails or by welding.
Typical sway bracings are illustrated in Figures 8.1.3(a) and Figure 8.1.4.
8.1.8
LATERAL BRACINGS
Lateral Bracings are made of steel or wood.
Lateral bracings are the transverse bracings between primary components such as
beams, girders, trusses and arches and are normally located in the horizontal
plane.
Lateral bracings are normally made from single components but sometimes may be made
into frames.
Typical lateral bracings are illustrated in Figures 8.1.3(a), 8.1.3(c) and Figure
8.1.8.
8.2
PRIMARY COMPONENTS
The following are to be considered as primary components:
-
beams, girders;
thick slabs;
truss top and bottom chords, verticals and diagonals;
arch ribs, ties, vertical and diagonals;
stringers and floor beams;
load bearing diaphragms that directly support or transmit wheel loads.
connections to primary components.
barrel of culverts, tunnels and soil-steel structures.
8.2.1
8.2.2
Performance defects in primary components are related to their ability to support
the dead and live loads imposed on them and to transmit those loads to the
substructure without excessive deformations or vibrations.
1-8-7
8.3
The following are to be considered as secondary components:
- Non-load bearing diaphragms that do not directly support or transmit wheel
loads;
- Sway bracings;
- Lateral bracings;
- Connections to secondary components.
- Inlet and outlet treatments of culverts.
8.3.1
8.3.2
The performance condition rating of non-load bearing diaphragms is based upon their
ability to restrict relative vertical and transverse movements between the primary
components and thus transmit vertical and transverse loads between them without
excessive or permanent deformations.
The performance condition rating of sway bracings is based upon their ability to
restrict relative transverse and vertical movements between primary components and
thus prevent lateral buckling of primary components.
The performance condition rating of lateral bracings is based upon their ability to
restrict relative longitudinal and transverse movements between primary components
and thus transmit longitudinal and transverse loads between them without excessive
or permanent deformations.
The performance condition rating of inlet and outlet treatments of culverts is
based upon their ability to provide for the functions they are designed for.
8.4
REFERENCES
1. The Bailey and Uniflote Handbook, 1974, Acrow Corporation of America
1-8-8
BEAMS & GIRDERS
TOP
FLANGE
TOP
FLANGE
TOP
FLANGE
BOTTOM
FLANGE
B
WE
BOTTOM
FLANGE
T - BEAM
CAST IN PLACE
PRECAST BOX BEAM
WELDED BEAM
ROLLED BEAM
HORIZONTAL
STIFFENER
VERTICAL
STIFFENER
PRECAST TRAPEZOIDAL GIRDER PRESTR. - GIRDER
CONCRETE BEAMS & GIRDERS
WELDED PLATE GIRDER RIVETED PLATE GIRDER
STEEL BEAMS & GIRDERS
L
RA
TE
L A CI NG
A
BR
KEY
ST
PRECA
CAST IN
PLACE
VERTICAL
STIFFENER
INTERIOR
DIAPHRAGM
SEGMENTAL BOX GIRDER
STEEL BOX GIRDER
WOOD BEAMS
SAWN
BOLT
LAMINATED
GLUED
LAMINATED
Figure 8.1.1
1-8-9
Beams and Girders
LONGITUDINAL
STIFFENER
Solid Thick Slab
ROUND VOIDS
RECANGULAR VOID
TRAPEZOIDAL VOID
Voided Thick Slab
Figure 8.1.2
1-8-10
Thick Slabs
TYPICAL WOOD TRUSSES
TYPICAL STEEL TRUSSES
ELEVATION
ELEVATION
SWAY
BRACING
C
SWAY
BRACING
SECTION
SECTION
HALF - THROUGH (PONY) TRUSS
DIAGONALS
VERITCALS
HALF THROUGH (WOOD) TRUSS
BOTTOM CHORD
TOP CHORD
ELEVATION
ELEVATION
SWAY BRACING
SECTION
THROUGH (WOOD) TRUSS
SECTION
THROUGH TRUSS
DIAGONALS
VERTICALS
TOP CHORD
ELEVATION
BOTTOM CHORD
BRACING OR
DIAPHRAGMS
LATERAL
BRACING
SECTION
DECK TRUSS
Figure 8.1.3(a)
1-8-11
Trusses
C
L
MAIN GIRDER
RAKER
A
TOP CHORD
BRACING FRAME
(TYP.)
VERTICAL
BRACING
FRAME
CL
TRANSOM
SINGLE SINGLE
TOP CHORD
BRACING FRAME
CL
TRANSOM
DOUBLE DOUBLE
TRANSOM
BRACING
FRAMES
WIDENED
FRAMES
DOUBLE SINGLE
TOP CHORD
BRACING
FRAME
C
L
CL
WIDENED TOP
CHORD BRACING
FRAME
STANDARD
BAILEY
PART
TIE PL
L
TIE P
(a)
TRANSOM
(a)
STANDARD
BAILEY PART
MODIFIED
BAILEY
PART
(b)
MODIFIED
BAILEY PART
(b)
TRIPLE DOUBLE
DIMENSION (A)
STANDARD BAILEY..................... 3759 mm
STANDARD WIDENED BAILEY... 4343 mm
TRIPLE SINGLE
Figure 8.1.3(b) Typical Bailey Configurations
1-8-12
Figure 8.1.3(c) Typical Bailey Components
1-8-13
TOP CHORD OR RIB
TOP CHORD OR RIB
SWAY BRACING
HANGERS
ELEVATION
ELEVATION
SWAY BRACING
SWAY BRACING
SECTION
SECTION
Concrete Bowstring Arch
Through Arch
ARCH RIB
ARCH RIB
ELEVATION
ELEVATION
CL
CL
SWAY
BRACING
COLUMNS
SECTION
Filled Sprandel Arch
MULTIPLE RIB
SINGLE RIB
SECTION
Open Sprandel Arch Steel or Concrete
Concrete Barrel Arch
Figure 8.1.4 Arches
1-8-14
Outlet
Barrel
Stream
Flow
Inlet
Figure 8.1.5(a)
Basic Culvert, Tunnel and Soil-Steel
Structure Components
wingwall
wingwall
headwall
headwall
cut-off wall
apron
stilling basin
energy
dissipators
Inlet
Figure 8.1.5(b)
Outlet
Typical Inlet and Outlet Components
1-8-15
Open Footing Concrete Culvert
Concrete Box Culvert
Wood Culvert
Figure 8.1.5(c)
Round Corrugated Pipe Culvert
Typical Culverts and Tunnels
1-8-16
Figure 8.1.5(d)
Typical Soil-Steel Structures
1-8-17
Apr. 2008
~
~
LOAD BEARING
DIAPHRAGM
~
NON-LOAD BEARING
DIAPHRAGM
LOAD BEARING DIAPHRAGM
IN STEEL BOX GIRDER
NON-LOAD BEARING
DIAPHRAGM
Figure 8.1.6 Diaphragms
TOP LATERAL
BRACING
1
1
GIRDER
GIRDER
1
BOTTOM
LATERAL
BRACING
LATERAL
BRACING
1
SECTION
1 PLAN
Figure 8.1.8 Lateral Bracing
1-8-18
SECTION 9
-
DECK COMPONENTS
Contents
9.1
Deck Components ...............................................
9.1.1 Decks ..................................................
9.1.2 Wearing Surfaces .......................................
9.1.3 Curbs and Sidewalks ....................................
9.1.4 Approaches and Approach Slabs and Ramps ................
9.1.5 Drainage and Deck Drains ...............................
9.2
Primary Components ............................................ 1-9-4
9.2.1 Material Defects of Primary Components ................. 1-9-4
9.2.2 Performance Defects of Primary Components .............. 1-9-4
9.3
Secondary Components .......................................... 1-9-4
9.3.1 Material Defects of Secondary Components ............... 1-9-5
9.3.2 Performance Defects of Secondary Components ............ 1-9-5
9.4
Auxiliary Components .......................................... 1-9-5
9.4.1 Material Defects of Auxiliary Components ............... 1-9-5
9.4.2 Performance Defects of Auxiliary Components ............ 1-9-5
9.5
References
9.1
DECK COMPONENTS
.................................................... 1-9-5
The following components are considered in this section:
-
Decks
Wearing Surfaces
Curbs and Sidewalks
Approaches and Approach Slabs and Ramps
Drainage and Deck Drains
9.1.1
DECKS
The types of decks commonly used are:
-
1-9-1
1-9-1
1-9-2
1-9-2
1-9-3
1-9-3
Reinforced Concrete Decks;
Wood Decks;
Orthotropic Steel Decks;
Open Grating Steel Decks; and
Corrugated Metal Sheeting Decks.
1-9-1
Reinforced concrete decks are the most common type of deck used in structures.
They are commonly cast-in-place but may also be pre-cast.
This type of deck
includes slab on beams, and the top surface of solid or voided thick slabs, or of
rigid frames.
Wood decks are commonly used on secondary roads and rural highways. Types of wood
decks commonly used include longitudinal and transverse laminated wood decks,
prestressed wood decks, plank decks and composite wood and concrete decks.
Orthotropic steel decks consist of a flat steel top plate surface welded to a
supporting system of steel girders, floor beams and ribs. Flat bars or studs are
often welded to the top steel plate to improve the bond with the wearing surface.
Prefabricated steel grating is sometimes used as decking material. The open mesh
grating panels are installed over a network of steel floor beams and stringers to
form the riding surface.
A variation of this deck is produced by placing a
concrete infill slab over the grating to form a composite deck surface.
Corrugated metal sheeting decks have been used in a few cases. They are normally
overlaid with asphalt or concrete wearing surface.
Figure 9.1.1 illustrates the types of decks commonly encountered.
9.1.2
WEARING SURFACES
The top surface of the deck is either left exposed and acts as the wearing surface
or is protected by an additional wearing surface. A waterproofing membrane placed
between the deck and asphalt wearing surface also provides additional protection.
Reinforced concrete and steel decks are typically covered with an asphalt wearing
surface, with or without waterproofing. Wood decks are typically covered with an
asphalt, concrete or wood planking wearing surface, normally without waterproofing.
Wearing surfaces are shown in Figure 9.1.1.
9.1.3
CURBS AND SIDEWALKS
Curbs and sidewalks are located parallel to the side limits of the roadway and are typically elevated
between 100mm and 250mm in height above the roadway surface. Both these components include a
vertical face and a horizontal portion. For the purposes of this manual, the only differentiation between
a curb and a sidewalk shall be width. A width of less than 1500mm shall be identified as a curb and
1500mm or greater shall be identified as a sidewalk. This definition is used, despite the fact the many
large curbs with widths of 600mm or more can safely accommodate pedestrians in rural areas. The
difference between curbs and sidewalks is illustrated in Figure 3.3 of Part 2.
Sidewalks and curbs are sometimes built on supports which cantilever beyond the deck limits. These
supports shall be inspected as part of the floor system (floor beams, stringers, etc.) while only the face,
top and bottom surfaces of the curb or sidewalk shall be included with the curb/sidewalk component.
1-9-2
Oct. 2000
Curbs and sidewalks can be constructed of concrete, wood, asphaltic concrete or
steel. Precast masonry is sometimes used as well.
Typical examples of curb and sidewalk construction are illustrated in Figures
9.1.1 and 9.1.3.
9.1.4
APPROACHES, APPROACH SLABS AND RAMPS
Approaches shall be inspected immediately adjacent to the structure. The length to be inspected
shall be the length of the approach slab, or the length to the end of the wingwall (whichever is
greater). For jurisdictions where separate inspection of roadway features are not performed, a
longer section of approach may be inspected for some elements (e.g. include approach guide-rail
or include longer length of approach sidewalk or curb).
Approach slabs are located at each end of the structure, however, they may not be
present at some structures on lightly travelled roads or on gravel roads.
Approach slabs, where present, are constructed upon the approach embankment. One
end of the approach slab is anchored to the ballast wall or abutment wall, the
other end rests upon the approach fill and is free to move.
Where approach slabs are present, they are often paved over with an asphalt wearing
surface.
Approach ramps are sometimes provided at the approach to Bailey bridges and shall be categorized as
approach slabs.
A typical concrete approach slab is illustrated in Figure 9.1.4.
9.1.5
DRAINAGE AND DECK DRAINS
Surface drainage on structures is channelled along the curbs and drained through
deck drains or allowed to drain off the deck. Drainage from the approaches is
normally drained into drainage ditches or caught at catch basins before it reaches
the structure.
Deck drains are usually located along the curb lines. Deck drains are typically
made of steel, although concrete, aluminum, acrylonitrile butadiene styrene (ABS)
and polyvinylchloride (PVC) are sometimes used as well. Steel drains are usually
galvanized or made of atmospheric corrosion resistant steel.
Deck drains are
anchored to the deck by metal bars, or rely on their shape and bonding forces to
secure them in place.
Deck drains vary in size and shape, and vary from single pipes to prefabricated
pipe and catch basin units.
Deck drains can also occur individually or be
interconnected to an extensive collection system terminating at storm sewers. In
either case, deck drains must extend below or away from structure components below
the deck to prevent water discharge or spray from falling on those components.
Deck drains, in concrete decks, normally have drainage holes in them, at the
interface between the deck top surface and the asphalt wearing surface, to drain
water that has penetrated through the wearing surface.
1-9-3
Apr. 2008
Concrete decks with dams at expansion joints usually have 25mm diameter PVC tubes
placed through the deck, from the interface of the wearing surface and deck top
surface, to drain water which penetrates through the wearing surface.
Precast concrete box girders and steel box girders have drain holes in the bottom
flange to drain off any water that finds its way into the boxes. These also serve
to provide ventilation.
Drainage ditches, gutters and catch basins in the approaches to the structure are
detailed in References 1 and 2.
Figure 9.1.5 illustrates typical examples of drainage systems and deck drains
commonly encountered.
9.2
PRIMARY COMPONENTS
Decks and wearing surfaces shall be considered as primary components.
9.2.1
The top surfaces of exposed decks are directly subject to the adverse effects of
weather, traffic and the use of de-icing salts and chemicals. This results in
rapid deterioration of the decks.
Even with the added protection of the wearing surfaces, the deck top surfaces below
the wearing surfaces of covered decks are often prone to similar deteriorations as
exposed decks. Unfortunately, the wearing surfaces may hide these defects on the
deck surfaces until they are well advanced.
9.2.2
Performance of decks relate to their ability to support imposed live and dead
loads, to transit those loads to the supporting superstructure components and to
provide safe and smooth riding surfaces for traffic.
Performance of wearing surfaces relate to their ability to provide safe and smooth
riding surfaces and to protect the underlying decks from deterioration.
9.3
Curbs, sidewalks, approaches, approach slabs and ramps are to be considered as
secondary components.
1-9-4
9.3.1
9.3.2
Performance of curbs and sidewalks relates to their ability to provide safe and
comfortable passage for pedestrians, and to protect structure components beyond the
roadway limits from vehicular collision and damage. Curbs also serve to channel
roadway surface drainage to deck drainage systems.
Performance of
provide smooth
approach slabs
embankment and
9.4
approaches, approach slabs and ramps relates to their ability to
transition for traffic onto and off the structure. Performance of
also relates to their ability to distribute live loads through the
to the abutment wall.
AUXILIARY COMPONENTS
Deck drains, drainage ditches, gutters and catch basins shall be considered as
auxiliary components.
9.4.1
MATERIAL DEFECTS OF AUXILIARY COMPONENTS
9.4.2
PERFORMANCE DEFECTS OF AUXILIARY COMPONENTS
The performance of deck drains and drainage systems relates to their ability to
remove water from the deck and approaches, and to direct and discharge it safely
away from the structure and its components.
Trapped or ponded water is a safety hazard, particularly when frozen, as it can
lead to loss of vehicle control. It can also result in deterioration of the deck
and other components.
Inadequate discharge of approach drainage results in erosion of the approach fills
and loss of support for structure components.
Deck drains and drainage systems discharging onto structure components result in
rapid deterioration of those components.
9.5
REFERENCES
1.
MTC Drainage Manual.
2.
Highway Engineering Standards - Roads, Barriers and Drainage.
1-9-5
WEARING
SURFACE
DECK
DECK
CAST IN PLACE
WITH OR WITHOUT VOIDS
Thin Deck Slabs
Thick Deck Slab
WOOD
COMPOSITE
WITH CONCRETE
WEARING
SURFACE
DECK
WEARING
SURFACE
LAMINATED
DECK
PRECAST UNITS
Concrete on Precast Beams
DECK PLATE
WELDED TO ALL
SUPPORT
MEMBERS
WOOD PLANK OR
LAMINATED DECK
WEARING
SURFACE
PLANK
DECK
Wood Decks
STEEL
GRATING
FLOOR BEAM
LONGITUDINAL
RIBS
Orthotropic Steel Deck
Figure 9.1.1
1-9-6
FLOOR BEAM
Open Steel Grating Deck
Typical Decks
CONCRETE CURB FACE
DECK
CURB OR
SIDEWALK
CONCRETE,TIMBER OR
PRECAST MASONRY
CURB
DECK
Curb With Sidewalk
Concrete Curb or Sidewalk
RAILING
RAILING
TIMBER CURB
FACE
TIMBER
DECK
STEEL CURB
FACE
TIMBER
SIDEWALK
STEEL
SIDEWALK
DECK
Timber Cantilever Sidewalk
Steel Cantilever Sidewalk
ASPHALTIC CONCRETE
CURB FACE
DECK
ASPHALTIC
CONCRETE
OVERLAY
Asphaltic Concrete Sidewalk
Figure 9.1.3
Typical Curbs and Sidewalks
1-9-7
APPROACH SLAB
BALLAST
WALL
APPROACH
EMBANKMENT
ABUTMENT
Figure 9.1.4
Concrete Approach Slab
1-9-8
PIER
ABUTMENT
CATCH BASIN
DECK DRAINS
CURB OR SIDEWALK
APPROACH SLAB
APPROACH ROAD
Plan
CATCH BASIN
DECK DRAINS
BELOW
DECK
DRAIN
DRAIN
SPLASH
PAD
ABUTMENT
DRAINS
Elevation
Drainage Systems
CURB OR SIDEWALK
DECK
CURB OR SIDEWALK
DECK
DRAIN
DECK
COLLECTOR
PIPE OR
TROUGH
ABUTMENT
OR PIER
DECK
HANGER
SUPPORT BRACKET
PIPE RING
DISCHARGE
FLEXIBLE
HOSE
SLOPED
COLLECTOR PIPE
DOWN PIPE
Figure 9.1.5
Drainage and Deck Drains
1-9-9
CURB OR
SIDEWALK
B
WEEP HOLES
ROUND OR
SQUARE
DRAIN PIPE
A
WEARING
SURFACE
METAL DRAIN PIPE
WITH BASIN
BASIN
A
CURB OR
SIDEWALK
PLAN
B
Drain Pipe With Basin
CURB OR
SIDEWALK
WEARING
SURFACE
DECK
METAL
DRAIN PIPE
(ROUND OR OVAL)
CONCRETE DRAIN
PIPE - ROUND
Drain Pipes Without Basins
Figure 9.1.5
Drainage and Deck Drains(cont'd)
1-9-10
BRIDGE DECK
SECTION 10
-
RAILING SYSTEMS
Contents
10.1
Railing Systems ............................................... 1-10-1
10.1.1 Material Defects of Railing Systems ................... 1-10-3
10.1.2 Performance Defects of Railing Systems ................ 1-10-4
10.1
RAILING SYSTEMS
Railing systems are to be considered as secondary components as they do not
normally contribute to the capacity of the structure, however, there are some
structures in which the parapet walls also act as the main beams.
In those
structures the parapet walls shall be considered as primary components.
Railing systems are located at the outermost side limits of the roadway or
sidewalk, and may also be located along the median for separation of two way
traffic.
Railing systems, post anchorages and rail connections are described below and
illustrated in Figure 10.1.
(a)
Parapet Walls
Parapet Walls are rectangular reinforced concrete walls. They commonly support
posts and two tube rails or other rail configurations on them.
(b)
Barrier Walls
New Jersey type barrier walls are reinforced concrete walls with a sloping front
face. Barrier walls on approaches may not be reinforced. Barrier walls 800 mm
high are provided with a top tube rail.
Barrier walls 1025 mm high are not
provided with a tube rail.
International Barrier Company (IBC) barrier walls are free standing zincgalvanized steel structures of cold formed profiles supported by interior steel
bulkheads and covered by galvanized steel lids. The exterior of the IBC barrier
may be vinyl coated. The interior of the IBC barrier is typically filled with sand
or gravel.
1-10-1
(c)
Railings
Railings consist of posts and rails and may be latticed, barred, balustered or
other open web configuration. Railings have been commonly used in conjunction with
curbs and sidewalks on structures with low volume or low speed traffic; and, on
structures built before about 1960. Their use was discontinued around that time on
structures on King's highway due to the greater protection provided by the
introduction of parapet walls and, later, barrier walls.
The following posts and railings are commonly encountered:
-
concrete posts and concrete rails;
concrete posts and steel rails;
concrete posts and aluminum rails;
concrete posts and steel flex-beam rails;
steel posts and steel rails;
steel posts and cable rails;
steel I-posts and steel box beam rails;
steel grillages;
corrugated steel box filled with sand;
aluminum posts and aluminum rails;
wood posts and wood rails;
wood posts and steel flex-beam rails;
wood posts and steel cables.
In railings using cables, splices may be used to join lengths of cable.
End
fittings and anchor blocks may also be provided to allow for tensioning of the
cables.
(d)
Splash Guards
Splash Guards are designed to protect pedestrians and railings from vehicular salt
and water splash; and, also serve to guide pedestrian traffic. Splash guards are
typically made from concrete, steel, aluminum or plastic.
(e)
Post Anchorages
The method of anchoring posts depends on the post material and on the time of
installation of the post relative to the construction of the deck or structure
component to which it is connected.
Reinforced concrete posts are usually cast monolithically with the deck, curb or
sidewalk, or are, subsequently, cast around reinforcing extending from them.
Steel posts are anchored by direct embedment or by anchor plates and bolts.
Embedded posts are often set into a steel socket and caulked with hot poured
sulphur and lead wool or grouted with non-shrink grout. Anchor plates and bolts
are generally used when the post is installed on an existing structure component.
1-10-2
Square hollow steel posts commonly used for steel railings were often partially
filled with concrete with a drainage hole made through the side of the post, just
above the level of the concrete, to prevent bursting of the post due to the
freezing of entrapped water. The top of the post was capped to prevent the entry
of water.
Aluminum posts are secured to the deck, curb or sidewalk by anchor bolts. Nylon
washers are required between the aluminum base plate and steel anchor bolts.
Wood posts are usually bolted to the side of the structure, or bolted in steel
anchor shoes which are bolted down to the deck, curb or sidewalk.
(f)
Rail Connections
Rails are secured to posts by bolts, set screws, nails, or reinforcing steel,
depending on the combination of rail and post material:
- steel rails used with steel, concrete or wood posts are usually bolted to the
post, steel rails sometimes pass through pre-drilled holes in steel posts;
- aluminum rails used with aluminum or concrete posts are usually bolted to the
posts;
- concrete rails used with concrete posts are cast monolithically with the
post, or may be precast;
- wood rails used with wood posts are usually nailed or bolted to the post;
- steel cable rails used with wood or steel posts are usually stapled to wood
posts; and, bolted to or pass through pre-drilled holes in steel posts.
Sleeves are provided between sections of continuous tube rails; and, slotted holes
are provided at bolted rail splices and rail to post connections, to allow for:
thermal expansion and contraction of the rail; structure movements; and,
construction tolerances. These provisions do not apply for cable rails or for all
concrete or all wood railing systems.
The ends of tube rails are capped to prevent water from entering and causing
corrosion inside the rail.
10.1.1
MATERIAL DEFECTS OF RAILING SYSTEMS
cables are:
-
In addition, defects in railings using
broken wires or entire cable;
loose cables or inadequate cable tension;
loose or corroded splices or fittings.
1-10-3
10.1.2
PERFORMANCE DEFECTS OF RAILING SYSTEM
The performance of barrier walls and railings is based upon their ability to
safeguard and guide vehicular traffic and pedestrians along the structure; and, to
deter the accidental passage of vehicles over the side of the structure, or into
oncoming traffic.
The performance of the top rail on parapet walls, barrier walls and railings is
based on its ability to provide a handrail for pedestrians, to withstand or absorb
some vehicular impact and to provide lateral support for some types of railings.
The performance of splashguards is based upon the
protection provided to
pedestrians or railing systems against salt and water splash directed by vehicles
passing in adjacent lanes.
The performance of railing systems shall also be based upon their present condition
with regards to their ability to meet the safety standards and other requirements
in effect at the time they were originally installed.
1-10-4
RAIL CAP
(TYP.)
RAIL SPLICE AND
EXPANSION JOINT
PEDESTRIAN RAIL
POST
BOTTOM RAIL
NYLON BUSHING
(ALUM.ONLY)
REINF. CONC.
PARAPET WALL
MASTIC COATING
(ALUM. ONLY)
STEEL ANCHOR BLOTS
Reinforced Concrete Parapet Walls (with rails)
PEDESTRIAN
RAIL
RAIL SPLICE AND
EXPANSION JOINT
RAIL CAP
(TYP.)
POST
NYLON
BUSHING
(ALUM.
POST)
STEEL
ANCHOR
BOLTS
Without Rail
MASTIC
COATING
(ALUM.
POST)
REINF. CONC.
NEW JERSEY
BARRIER WALL
With Rail
Reinforced Concrete New Jersey Barrier Wall
Fill - usually sand and/or gravel
Lid
Strap Nut
Steel Panel
Interior
Steel
Bulkhead
Opening for Road Drains
International Barrier Company (IBC) Barrier
Figure 10.1
Railing Systems
1-10-5
POST CAP
TOP RAIL CONNECTION
WITH SLOTTED HOLE
FOR EXPANSION
HOLLOW
STEEL
POST
BENT PLATE
STEEL PEDESTRIAN
RAIL
TOP OF
CONCRETE
DRAINAGE
HOLE
STEEL CHANNEL
CONCRETE
POST
STEEL
POST
CONCRETE
DECK
PEDESTRIAN
RAIL
BOT. RAIL CONNECTION WITH
SLOTTED HOLE FOR EXPANSION
Steel Railing
TOP
TRAFFIC
RAIL
RAIL SPLICE
& EXPANSION
JOINT
MIDDLE
TRAFFIC
RAIL
BOTTOM
TRAFFIC
RAIL
3-RAIL
ANCHOR BOLT
4-RAIL
JOINT
COVER
TRAFFIC RAILS
Metal Railing (Steel or Aluminum)
ALUM.
BALLISTERS
BENT PLATE ALUM.
PEDESTRIAN RAIL
TOP RAIL
CONNECTION
ALUM. H POST
BOTTOM RAIL
CONNECTION
BASE
PLATE
CONCRETE DECK
ANCHOR
BOLT
Figure 10.1
STEEL CHANNEL
Aluminum Railing
Railing Systems (cont'd)
1-10-6
REINF. CONC
POST
REINF.
CONC.
RAIN
CONC.
DECK
Reinforced Concrete Railing
REINF. CONC.
RAIL
REINF.
CONC. POST
RECESS FOR
RAIL
CONC
DECK
Reinforced Concrete Railing
CABLE END CONNECTION
& TENSION DEVICE
STEEL ANGLE
POST
STEEL
ANGLE
POST
STEEL
CABLE
DECK
ANCHOR
BOLT
ANCHOR
BOLTED
EMBEDDED
Steel Post and Cable Railing
Figure 10.1
1-10-7
STEEL
SPIKES
STEEL
SPIKES
WOOD
RAILS
PEDESTRIAN RAIL
STEEL CONNECTING
BOLTS (TYP.)
TRAFFIC RAILS
WOOD POST
WOOD
DECK
ANCHOR
BOLTS
Wood Railing
ALUMINUM OR
STEEL PIPE
CORRUGATED GALV. STEEL
ALUMINUM OR PLASTIC
SHEET PANEL
ALUMINUM OR
STEEL PIPE
EMBEDDED OR
ANCHOR BOLTED
Railing With Splash Guard
Figure 10.1
1-10-8
WOOD
OFFSET
BLOCK
OFFSET
BLOCK
WOOD
POST
SLOTTED HOLE
& SPLICE
BOLT
STEEL BEAM
GUIDE RAIL
WOOD POST
POST
BOLT
SLOTTED HOLE
AND BOLT
RECTANGULAR
WASHER
STEEL
CHANNEL
~
POST
CONNECTION
BOLT
~
STEEL
POST
BASE
SLOTTED HOLE & SPLICE BOLT
SPLICE PLATE
DRAIN
HOLE
ALONG MEDIAN
ALONG EDGE
OF ROADWAY
WEARING
SURFACE
ANCHOR
BOLT
Wood Post and Steel Flex-Beam Rail
SPLICE CONNECTION
STEEL PLATES
SPLICE BOLT
STEEL BOX
BEAM RAIL
POST
BOLTS
SPLICE
PLATE
STEEL POST
Steel Post and Box Beam Rail
METAL
POST
STEEL
BASE
PLATE
CAULK WITH
LEAD WOOL
CONC.
DECK
METAL POST
STEEL OR
NEOPRENE
SHIM
CONC.
DECK
CAULK WITH HOT
POURED SULPHUR
STEEL SOCKET
ANCHOR BOLT
STEEL PLATE
CAP
EMBEDDED
Metal Post Anchorage Details
Figure 10.1
BOLTED
1-10-9
STEEL BEAM
GUIDE RAIL
WOOD OFFSET BLOCK
BOLT
REINF. CONCRETE RAIL
CONCRETE
DECK
Concrete Post with Steel Flex-Beam and with
Concrete Rail
STEEL STAPLE
STEEL CABLES
POST
SPICER
POST
STEEL
BASE
BOLT
ANCHOR
BOLTS
DRAIN
HOLE
EARTH
CONCRETE
DECK
Wood Post and Steel Cable
Figure 10.1
1-10-10
END
FITTING
SECTION 11 - STRUCTURAL STEEL COATINGS
CONTENTS
11.1
Structural Steel Coatings ................................... 1-11-1
11.1.1 Material Defects of Coatings ................ 1-11-3
11.1.2 Performance Defects of Coatings ......... 1-11-3
11.2
11.1
References ......................................................... 1-11-4
STRUCTURAL STEEL COATINGS
Structural steel coatings are to be considered as primary or secondary components based upon the designation of
the component that is coated. The following coatings and coating systems have been used on provincial steel
structures (References 1 to 5).
(a)
3 Coat Alkyd System (discontinued)
This system was used on most coated steel bridges until about 1974 when it was discontinued. It
consisted of:
-
(b)
red lead primer;
light grey second coat;
green top coat;
Inorganic-Zinc/Vinyl System (discontinued)
This system has been used since about 1982 on a number of coated steel bridges. It consists of:
-
(c)
reddish grey to greenish grey inorganic zinc primer;
reduced vinyl wash second coat or proprietary tie coat, in white, green or grey;
green high build vinyl third coat;
high build vinyl topcoat, usually grey in colour, sometimes green.
Epoxy-Zinc/Vinyl System (discontinued)
This system was used on coated steel bridges starting in 1987. It consists of:
-
(d)
green or reddish grey organic zinc primer;
high build vinyl second coat, in green or light grey;
high build vinyl top coat, grey in colour.
Aluminum-Filled Epoxymastic System
This system has been used since about 1982 on a number of coated steel bridges. It has also been used in
selected locations on atmospheric corrosion resistant (weathering) steel, under expansion joints. It was
discontinued in 1988. It consists of:
-
two coats of aluminum coloured epoxy mastic.
1-11-1
Nov. 2003 Revision
(e)
Inorganic-Zinc/Epoxy/Urethane System
This low VOC system has been used on coated steel bridges since 1996. It consists of:
-
(f)
reddish grey to greenish grey inorganic zinc primer;
an epoxy second coat, green or white;
urethane top coat, grey in colour.
Epoxy-Zinc/Epoxy/Urethane System
This low VOC system will be used on coated steel bridges starting in 1990. It consists of:
-
(g)
green or reddish grey organic zinc primer;
an epoxy second coat, in green or white;
urethane top coat, grey in colour.
Inorganic Zinc/Acrylic/Acrylic
This system is one of the low VOC systems that is in the DSM list for coating structural steel. It has only
been used on a few bridges. It consists of:
-
(h)
greenish grey inorganic zinc primer;
buff acrylic mid coat;
grey acrylic topcoat.
Epoxy-Zinc/Acrylic/Acrylic
This system is one of the low VOC systems that is in the DSM list for coating structural steel. It has only
been used on a few bridges. It consists of:
-
(i)
greenish grey organic (epoxy) zinc primer;
buff acrylic mid coat;
grey acrylic topcoat.
High Build Alkyd System
This system was used on most coated steel bridges from about 1974 to 1985. Its use has virtually been
discontinued. It consists of:
-
(j)
yellow zinc chromate primer, one or two coats;
green high build alkyd top coat (for handrails); or
grey high build alkyd topcoat (for other steelwork).
Hot Dip Galvanizing
Galvanizing has been used since about 1970 on Bailey bridges and on handrails. It consists of zinc
applied to steel in a variety of methods and has a fairly smooth, large grain, shiny to semi-dull surface
appearance.
1-11-2
Nov. 2003 Revision
(k)
Metallizing
Metallizing has been used since about 1970 on Bailey bridges and on handrails. It consists of a sprayed
coating of zinc or zinc/aluminum and has a coarse or gritty surface appearance resembling sandpaper. It
has also been used to recoat the girders of one bridge.
(l)
Coal Tar Epoxy
This system has been used in the past on the inside of some box girders. It is black or dark brown in
colour.
(m)
Coal Tar for Piles
This system has been used in the past on the inaccessible areas of steel behind abutment diaphragms and
on steel piles. It is black in colour.
11.1.1 MATERIAL DEFECTS OF COATINGS
11.1.2 PERFORMANCE DEFECTS OF COATINGS
The performance of coatings is based upon the ability of the coating to protect the component against
deterioration resulting from direct exposure to elements in the environment; such as, moisture, de-icing salts, and
airborne abrasives, pollutants and contaminants.
This degree of protection may be provided by a less than desirable material condition of the coating; however,
increasing material defects and deterioration will ultimately result in loss of protection provided by the coating or
coating system.
The rate of deterioration of the coating depends on the degree of exposure of the component to the destructive
elements.
In addition, where identical exposure conditions prevail, the following features can also affect the rate of
deterioration of the coating, namely:
-
horizontal surfaces usually deteriorate at a faster rate than vertical surfaces;
-
outside corners and edges of components usually exhibit greater deterioration, as coating thickness is
often less at these locations;
-
poor surface preparation or inadequate coating thickness, usually due to poor workmanship or difficult
accessibility of the surface.
-
the amount of time the steel is damp and the degree to which the component is ventilated also has an
effect.
1-11-3
Nov. 2003 Revision
11.2 REFERENCES
1.
Technical Data on Approved Coating Systems Designated Sources List DS: 113, MI-72. Materials
Information, Engineering Materials Office, M.T.C.
2.
SSPC Painting Manual, Volume 2 (4th Edition), Good Painting Practice, SSPC the Society for
3.
SSPC Painting Manual, Volume 2 (8th Edition), Systems and Specifications, SSPC the Society for
4.
Ridley, Grant, “Laboratory Evaluation of Low VOC Coating Systems for Abrasive Blast Cleaned
Steel”, Nov. 1993, Internal Report, Ministry of Transportation, Chemical Section, Material
Engineering and Research Office, Building C, 1201 Wilson Avenue, Downsview.
5.
Ministry of Transportation Structural Steel Coating Manual, 2003 Revised Version.
1-11-4
Nov. 2003 Revision
SECTION 12
-
SIGNS
Contents
12.1
Signs ........................................................ 1-12-1
12.1.1 Defects of Signs ..................................... 1-12-3
12.2
References
12.1
SIGNS
................................................... 1-12-3
The signs most commonly used to indicate restrictions at structures are described
below and shown in Figure 12.1.
Where signs are available in two sizes, the
oversize signs are used on Provincial Highways. They may also be used on other
equally important high speed roadways or at locations where greater visibility or
impact of the sign is required.
A full description of these signs and their application is contained in References
1, 2 and 3.
a)
Narrow Structure Signs
The Narrow Structure sign is used to indicate a bridge culvert, subway, overpass or
similar structure having a clear roadway width of 5 to 6 m inclusive or any
structure with a roadway clearance less than the width of the approach pavement.
The Narrow Structure sign is erected not less than 150 m nor more than 250 m in
advance of the structure.
It is available in two sizes.
Hazard Markers shall be used with the narrow structure signs.
b)
One Lane Signs
Where the structure has a clear roadway width of less than 5 m, thereby permitting
only a single lane of traffic, a tab sign reading "One Lane" is added immediately
below the Narrow Structure sign.
The "One Lane" tab sign may also be used where the structure roadway width is less
than 5.5 m when commercial vehicles constitute a significant proportion of the
traffic using the structure or when the alignment approaching the structure is
poor.
1-12-1
c)
One lane Only When Used by Trucks Signs
"One Lane Only When Used By Trucks" sign is used to supplement the Narrow Structure
symbol sign where the shape of the subway or the curvature of the road requires
trucks to swing to the centre of the roadway in order to pass through. It may also
be used where the structure roadway width is less than 5.5 m when commercial
vehicles constitute a significant proportion of the traffic using the structure, or
where the alignment approaching the structure is poor.
It is erected approximately 50 m beyond the Narrow Structure Symbol Sign.
d)
Hazard Marker Signs
Hazard Marker signs are used to mark structure limits when they are within 2 m of
the edge of the roadway in conjunction with the Narrow Structure sign.
Left or right hazard markers are erected with the stripes sloping at an angle of 45
degrees down towards the edge of the travelled portion of the roadway.
The right marker is always used to the right of traffic and left marker to the
left.
Left and right hazard marker is used where traffic may pass on both sides of an
obstruction.
e)
Low Clearance Signs
The Low Clearance signs, indicating low overhead clearance and showing the exact
amount of clearance at low bridges, underpasses and other structures, are used at
all points where clearance from the roadway to the low point of the structure is
less than 4.5 m.
The Clearance sign is erected, if possible, on the structure just above the opening
and over the centre of the roadway unless the clearance across the structure varies
between the centreline and the curb or edge of pavement, in which case a second
sign is erected to indicate the lesser clearance. Where there is a difference in
clearance across the structure and the roadway is considered "one lane" when used
by trucks, there shall be three signs posted; at the centreline and each edge of
pavement.
The Advance clearance sign is located not less than 100 m nor more than 250 m in
advance of the subway. The advance clearance sign is available in two sizes.
f)
Maximum Weight Signs
Single maximum weight signs and multiple maximum weight signs are erected to limit
the gross weight on bridges under the authority of an Ontario Regulation or a
Municipal Bylaw approved by the Ministry as per the Highway Traffic Act and
Directive B-43, Maximum Weight On Bridges Sign.
Regulatory maximum weight signs have black legend, symbols and border on white
reflective background.
1-12-2
Advisory maximum weight signs have black legend, symbols and border on yellow
reflective background.
g)
Others
There may also be other signs at structures, such as, speed restriction, slippery
when wet, bailey bridge ahead, marine warning lights and signs.
12.1.1
DEFECTS OF SIGNS
The following are some of the typical defects in signs:
-
loose, broken or missing components;
illegible;
not located according to standards;
gives misleading, wrong or inaccurate information;
not a standard sign.
12.2
REFERENCES
1.
Manual of Uniform Traffic Control Devices for Ontario, Division 5.
2.
The Highway Traffic Act - Government of Ontario
3.
Ministry Directive B-43
-
Maximum Weight On Bridges Sign
1-12-3
(75 x 75) cm or (90 x 90) cm
(a) Narrow Structure Sign
(c)
(b)
One Lane Sign
(90 x 90) cm
One Lane Only When Used by Trucks Sign
Figure 12.1
1-12-4
Signs
(d)
Hazard Marker Signs
Figure 12.1
1-12-5
Signs (cont'd)
(60 x 90) cm
Clearance Sign
(60 x 60) cm or(90 x 90) cm
Advance Clearance Sign
(e)
Low Clearance Signs
Single Posting Sign
(f)
Multiple Posting Sign
Maximum Weight Signs
Figure 12.1
1-12-6
Signs (cont'd)
SECTION 13
-
ATTACHMENTS
Contents
13.1
13.2
13.1.1
Attachments
13.1.1
Utilities ............................................
13.1.2
Electrical ...........................................
13.1.3
Bridge Mounted Sign Supports .........................
13.1.4
Noise Barriers .......................................
13.1.5
Other Attachments ....................................
Defects of Attachments .........................................
1-13-1
1-13-1
1-13-1
1-13-1
1-13-1
1-13-2
UTILITIES
Utilities most commonly hung from, attached to, or installed in the structure are:
Water mains
Gas mains
Bell ducts
Hydro lines
A variety of attachment methods are used to install these utilities on the
structure.
13.1.2
ELECTRICAL
This category is not used by the Ontario Ministry of Transportation (MTO) since MTO
Maintenance Contractors inspect electrical installations in accordance with the
Electrical Engineering Manual, Volume 2 – Electrical Maintenance.
This
category
inspections
attachments
-
can be used by jurisdictions that do not perform separate
of their electrical attachments to their structures.
Electrical
to bridges generally are:
Light Poles
Underpass Lighting
Cathodic Protection Conduits
A variety of attachment methods are used to install these accessories on the
structure.
13.1.3
BRIDGE MOUNTED SIGN SUPPORTS
This category is not used by the Ontario Ministry of Transportation (MTO) since MTO
inspects Bridge Mounted Sign Supports separately in accordance with the Sign
Support Inspection Guidelines.
This category can be used by jurisdictions that do not perform separate inspections
of their bridge mounted sign supports.
1-13-1
Apr. 2008
13.1.4
NOISE BARRIERS
Noise barriers on bridges typically have posts anchored to the barrier wall with
panels between the posts.
13.1.5
OTHER ATTACHMENTS
Other attachments can include:
Banner mounting hardware on bridges,
Fixed Automated Spray Technology (FAST)for de-icing
13.2
DEFECTS OF ATTACHMENTS
The following are some typical defects of attachments:
loose, broken or missing components;
cracks in anchorages, connections or clamps;
corrosion (i.e. on clamps, posts or steel noise barriers);
concrete deterioration such as scaling, spalling, etc. (i.e. on noise
barriers);
mechanical damage;
other visually apparent defects which may cause the attachment(s) to
fail resulting in loss of support.
1-13-2
Apr. 2008
SECTION 14
-
LIVE LOADS
Contents
14.1
Live Loads
................................................. 1-14-1
14.2
Design Live Loads
14.3
Evaluation Loads
14.4
References
14.1
LIVE LOADS AND POSTING PROCEDURES
.......................................... 1-14-1
........................................... 1-14-2
................................................. 1-14-2
This section gives historical information on design and evaluation live loads.
14.2
DESIGN LIVE LOADS
Design live loads from 1917 to present date are shown in Table 14.2 (References 1,
2, 3, 4, 5, and 6).
Design live loads prior to 1917 are not documented. In general, truck loads of 15
tons or less were used depending on the age of the bridge and the class of highway.
The time periods in Table 14.2 refer to the years during which a particular loading
was widely used in Ontario. The higher loads were normally used first for the
major highways and later introduced on the other road systems.
For example, HS20-16 was first used in 1953 for bridges designed for the Trans
Canada Highway followed in 1956 for bridges designed for Provincial Highways. By
1960 it was being used for all bridges designed for the Municipalities as well,
except a few in remote areas.
Similarly, bridges on Provincial Highways have been designed by OHBDC since 1979,
whereas, most bridges owned by the municipalities are still being designed to HS2016.
The design loads are documented to provide the inspectors with experience in
relating actual loading conditions to design loads.
1-14-1
14.3
EVALUATION LOADS
Evaluation loads, Table 14.3, were introduced in Ontario in 1979. Prior to that
evaluation of bridges for load carrying capacity was normally based on the design
loads.
14.4
REFERENCES
1.
General Plans for Steel Highway Bridges
The Department of Public Highways, Ontario, 1917
2.
General Specifications for Steel Highway Bridges
The Department of Public Highways, Ontario, 1923
3.
General Specification for Highway Bridges. Ontario
4.
Design of Bridges, CSA Standard S6.
5.
Standard Specification for Highway Bridges.
6.
Ontario Highway Bridge Design Code - 1979, 1983
Ministry of Transportation and Communications
1-14-2
-
1935
Canadian Standard Association
AASHTO
1-14-3
Table 14.2 – DESIGN LIVE LOADS
1-14-4
Table 14.2 (con’t) – DESIGN LIVE LOADS
1-14-5
1-14-6
Part 2 – Detailed Visual Inspections
PART 2 - DETAILED VISUAL INSPECTIONS
CONTENTS
Page
SECTION 1
OVERVIEW OF VISUAL INSPECTIONS..............................................................2-2
SECTION 2
ELEMENT LIST .......................................................................................................2-7
SECTION 3
ELEMENT QUANTITY CALCULATIONS .........................................................2-13
SECTION 4
MATERIAL CONDITION STATE TABLES........................................................2-28
SECTION 5
SUSPECTED PERFORMANCE DEFICIENCIES ................................................2-40
SECTION 6
MAINTENANCE NEEDS ......................................................................................2-45
SECTION 7
INSPECTION FORMS ...........................................................................................2-46
SECTION 8
EXAMPLES ............................................................................................................2-53
APPENDIX A
COMBINED MATERIAL DEFECT AND CONDITION STATE TABLES .....2-106
2-1
Apr.
2008
Oct. 2000
SECTION 1 - OVERVIEW OF VISUAL INSPECTIONS
Contents
Page
1.1
Qualifications of Inspectors ..........................................................................................................2-2
1.2
Responsibilities of Inspectors .......................................................................................................2-2
1.3
Safety Requirements .....................................................................................................................2-3
1.4
Inspection Equipment....................................................................................................................2-3
1.4.1 Standard Equipment Carried by Inspectors ...............................................................2-3
1.4.2 Special Access Equipment Requirements .................................................................2-3
1.5
Systematic Inspection Procedures ................................................................................................2-4
1.5.1 Preparation Prior to Field Inspection.........................................................................2-4
1.5.2 Site Inspection ...........................................................................................................2-4
1.5.3 Post Inspection Procedures........................................................................................2-5
1.1
QUALIFICATIONS OF INSPECTORS
Detailed visual inspections of structures should be carried out by:
•
•
1.2
Professional Engineers with a background in inspection, design and construction of bridges, or
Trained bridge inspectors reporting to, or under the supervision of, a Professional Engineer
RESPONSIBILITIES OF INSPECTORS
The main responsibilities of inspectors are:
•
•
•
•
•
•
•
•
Inspecting all elements that comprise the structure (See Sections 2 and 3),
Recording all areas of material defects for each element, and categorising them under a defined Condition State
(See Section 4),
Identifying suspected performance deficiencies (See Section 5),
Noting areas of the structure where maintenance is required (See Section 6),
Making recommendations for repairs and rehabilitation of the structure (See Section 7),
Indicating the suggested time frame or urgency of the proposed work (See Section 6 and 7),
Identifying additional detailed investigations that are required (See Section 7 and Part 3),
Ensuring that appropriate actions are taken or initiated to address safety concerns (see Part 1, Section 1.2.2 and
Part 2, Section 1.5.3).
2-2
Apr. 2008
Nov. 2003 Revision
1.3
SAFETY REQUIREMENTS
Inspectors shall take proper safety precautions and comply with the appropriate safety and traffic control legislation,
regulations, manuals and guidelines such as the Occupational Health and Safety Act, The Manual of Uniform Traffic
Control Devices, Safety Practices for Structure Inspections, etc. The specific requirements of these safety and traffic
control guidelines and procedures are not covered in this manual.
1.4
INSPECTION EQUIPMENT
1.4.1
STANDARD EQUIPMENT CARRIED BY INSPECTORS
All inspection personnel should be equipped with and be thoroughly familiar with the use of the following
equipment:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Binoculars
Camera and Film(s) or Digital Camera
Chalk, Markers and Paint Markers
Inspection Forms and Clip Boards
Flashlight (focussing type)
Length of Chain (2 m)
Light Chipping Hammer
Measuring Tape (3 m)
Measuring Tape (30 m)
"Workers Ahead” signs
Mirror on a Swivel Head with an Extension Arm
Plumb Bob
Pocket Knife or Multi-tool
Range Poles
Safety Belts and Lanyard
Boots, Hat, Gloves, Vest
1.4.2
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Flotation Vest
Safety Cones and Flashing Light
Scraper
Screwdriver (large)
Sounding Line (lead line)
Straight Edge (1 m)
Air Thermometers
Wire Brush
Re-chargeable Drill with Bits
Grinder
Wood Borer and Treated Plugs
Eye Level and Hand Level
String-line
Other Equipment as required
SPECIAL ACCESS EQUIPMENT REQUIREMENTS
Certain locations on a structure may not be accessible for inspection without special equipment. This special access
equipment may only be required on some structures periodically during Enhanced OSIM inspections and not during
all biennial inspections (see Part 1, Section 1.3.2). Inspectors should prearrange with the appropriate parties, for the
use of the special equipment such as:
•
•
•
•
•
•
Extension or Folding Ladder (3.5 m)
Boat or Barge
Scaffolds - mobile, cable supported or stationary
Scissors Lift
Truck mounted inspection bucket on a hydraulically operated boom off a truck
• "Cherry Picker"
• Ministry's "BridgeMaster"
Lane Closures
2-3
Apr. 2008
Nov. 2003 Revision
1.5
SYSTEMATIC INSPECTION PROCEDURES
1.5.1
PREPARATION PRIOR TO FIELD INSPECTION
The inspector shall:
•
Obtain and review existing records of the structure prior to field work, including design and "as-built" drawings,
previous inspection reports, correspondence and details of repairs, rehabilitations or modifications carried out
after original construction. It is often useful for the inspector to take to the field a one or two page summary of
general inventory data and information on previous rehabilitation work. See Section 7 for a sample of this type
of inventory data.
•
Prepare inspection forms, (See Section 7) for each structure to be inspected. An individual inspection report can
be built up, for any structure, by selecting the elements required to completely describe the structure under
consideration (See Section 2).
•
Record dimensions and calculate the quantities for the bridge elements under consideration as described in
Section 3. This information should be summarized on Page 4 in the “Element Data” section of the inspection
form (See Section 7). In certain cases, elements shall be divided into sub-elements as indicated in Section 2.
•
Decide the time schedule for the inspection and any required special equipment, including traffic protection
devices.
•
Make arrangements for special equipment and traffic control devices, if required.
•
Obtain permission from the railway company if the bridge is over railway tracks, and mobile platforms or other
special equipment is going to be used in the track area.
1.5.2
SITE INSPECTION
• Complete a brief overview inspection of the site to:
Assess the overall integrity of the structure and identify areas where more detailed examination may
be required
Observe the bridge under truck loading and identify any abnormal flexibility, deflections or noises
(rattling or vibration of members, etc)
Look for abnormal deflections, settlements or rotations by looking along the rail or barrier wall or
other members
Identify obstacles that may either interfere with the inspection or indicate a need for additional
special equipment.
•
Discuss inspection procedures with the foreman of the traffic crew so that adjustments, lane closures and traffic
detours, etc. are timed to suit inspection needs.
•
Check that all signs, temporary barriers, protective screens, etc. are in place.
•
Once the site has been secured, the inspection of each element (as selected in Section 1.5.1) shall proceed in a
systematic fashion (top to bottom of structure or bottom to top) by completing the various parts of the inspection
form. (See Section 7). Material defects, performance deficiencies, maintenance needs, recommended work and
time frame for work shall be noted for each element.
2-4
Apr. 2008
Nov. 2003 Revision
•
The inspector has the choice of inspecting all the spans of a structure together or “span by span”. If the
condition of each span varies considerably from one span to the next, then the inspector should inspect each
span separately. Element data would then be recorded separately for each span. Note that if the “span by span”
option is chosen, element dimensions and quantities should be recorded for the span under consideration only.
•
In general, if several elements of the same type exist for one structure (e.g. Piers, abutments), one “Element
Data” table can be used unless the condition of each of the elements varies considerably. If element condition
does vary, separate “Element Data” tables should be used and the “Location” part of the inspection form should
be filled in to distinguish one element from the next (e.g. North Abutment and South Abutment).
•
Sub-elements, as defined in Section 2, should be used in dividing up the structure, calculating
quantities and during the inspection.
•
If elements are changed or added in the field, element quantities must be adjusted accordingly.
•
Record observations and make sketches where appropriate.
•
Take photographs to adequately describe the structure and the defects found. In general, the following
photographs should be taken:
•
One photograph which clearly shows the deck cross-section and features such as number of traffic
lanes, curbs and sidewalks, medians and railing system. Note: This photograph is normally taken from
the approach roadway looking along the length of the bridge.
•
One photograph of the elevation of the structure which clearly shows the number of spans and
superstructure type.
•
One photograph of the underside (soffit) which shows the type and number of main superstructure
element(s).
•
Individual photographs should be taken of all areas in a poor condition state (areas with severe defects
and deterioration). These photographs should be taken at sufficiently close range such that the type,
location and extent of the defects are clearly visible and apparent. Note: Where there are no areas of
severe deterioration in an element, then a photograph should be taken showing a typical area which
represents the worst condition state in that element.
•
Check if the structure and its elements are built in accordance with existing available information and record any
significant discrepancies, so that existing records can be revised accordingly. If changes have taken place as the
result of rehabilitation work, element dimensions and quantities should be updated.
•
Identify additional detailed investigations that are required.
1.5.3
POST INSPECTION PROCEDURES
•
Ensure that the appropriate action is taken (notify bridge owner immediately) for any critical structural defects
or deficiencies (i.e. fatigue cracks in steel, imminent deck punch through, etc.) and all other unsafe conditions
that are discovered in the field,
2-5
Apr. 2008
Nov. 2003 Revision
•
Make sure all inspection equipment and temporary traffic control devices are removed from the site and the site
is left in workmanlike order,
•
Ensure the appropriate follow-up action is taken for any Suspected Performance Deficiencies noted during the
inspection,
•
Submit Maintenance Needs list to maintenance crew for action,
•
Ensure additional investigations are initiated in the timeframe recommended,
•
Write all necessary follow-up correspondence and reports.
2-6
Apr. 2008
Nov. 2003 Revision
SECTION 2 – ELEMENT LIST
The first step in performing a detailed visual inspection is to divide the structure into individual elements. Bridge
components, as described in Part 1 of this manual, have been grouped into elements where convenient. Although
primary, secondary and auxiliary components are described in Part 1, for inspection purposes, no distinction is made
between these types of components. Table 2.1 lists the standard elements available for each element group. Table
2.1 also gives the standard unit of measurement for quantities for each element and the appropriate Condition State
Table for categorising material defects. Table 2.2 lists the elements that are typically required for the most common
types of structures. It should be noted that this list is for guidance only. The actual element list should be customised
to suit the structure being inspected. For an explanation of what components of the structure are included under each
element category, refer to Table 3.1 in Section 3. The following general guidelines should be followed when
selecting elements:
•
Similar element types, within the same Element Group, should be grouped together, and a separate “Element
Data” table should be filled out for each element type (e.g. similar bearing types, diaphragm types, etc).
•
If element condition varies for similar element types, separate “Element Data” tables” should be used and the
“Location” part of the inspection form should be filled in to distinguish one element from the next (e.g. North
Abutment and South Abutment).
•
Elements should be divided into “sub-elements”, as shown in Table 2.2. The definitions for sub-elements are
given in Table 3.1. A separate “Element Data” table should be filled out for each sub-element. The following
sub-elements should be used:
•
For structures with expansion joints, an “End” element must be used for the superstructure element(s) (deck,
girder, etc). Each “End” shall be rated separately from the “Middle” portion of that element. An “end”
element is defined as having a length of 1 to 3 metres. The length should be selected based on the extent of
deterioration in the element end. An assumption of 2 metres can be made initially and adjusted in the field
afterwards. If the length of the end element is changed, the quantity calculations, as described in Section 3,
should also be adjusted accordingly.
•
For deck soffits, “Exterior” cantilevers shall be rated separately from the “Interior” of the soffit.
•
For diaphragms, floor beams and stringers, “End” and “Intermediate” sub-elements shall be used.
•
For barrier/parapet walls, the “Interior” face shall be rated separately from the “Exterior” face.
•
At this stage, a decision should also be made regarding the overall process for inspecting the bridge. Section 1.5.2
describes the criteria for selecting whether the bridge should be inspected as a whole or span by span.
•
The element list in Table 2.1 includes the most common bridge components. If a particular component is not
found in the element list, the most appropriate (closest match) element should be selected from the list. The
“Location” part of the inspection form can also be used when trying to identify non-standard elements.
2-7
Oct. 2000
Table 2.1: Element List and Condition State Cross Reference Table
Element
Group
Abutments
Accessories
(Attachments
and Signs)
Approaches
Barriers
Beams/Main
Longitudinal
Elements
Bracing
Coatings
Culverts
Decks
Embankments
& Streams
Foundations
Joints
Piers
Element Name6,7,8
Unit for
Quantity1,2,3, 4
Abutment walls
Sq.m.
Ballast walls
Sq.m.
Bearings
Each
Wingwalls
Sq.m.
Bridge Mounted Sign Supports9 Each
Electrical9
Each
Noise Barriers
m10
Other
Each
Signs
Each
Utilities
Each
Approach slabs
Sq.m.
Barriers9
m10
Curb and Gutters
m.
Drainage System
Each
Sidewalk/Curbs
Sq.m.
Wearing surface
Sq.m.
Barrier/Parapet Walls
Sq.m.
Hand Railings
m10
Posts
Each
Railing Systems
m10
Diaphragms
Each (Sq.m if
Concrete)
Floor beams
Sq.m.
Girders
Sq.m.
Inside boxes (sides & bottom) Sq.m.
Stringers
Each
Bracing
Each
Railing Systems / Hand Railings Sq.m.
Structural Steel
Sq.m.
Barrels
Sq.m.
Inlet Components
Sq.m.
Outlet Components
Sq.m.
Deck Top
Sq.m.
Drainage System
Each
Soffit – Inside Boxes
Sq.m.
Soffit – Thick slab
Sq.m.
Soffit – Thin Slab
Sq.m.
Wearing Surface
Sq.m.
Embankments
Each
Slope protection
Each
Streams and Waterways
All
Foundation (below ground level) N/A
Armouring/retaining devices
m.
Concrete end dams
Sq.m
Seals/sealants
Each
Bearings
Each
2-8
Applicable Condition State Table Number 5
4.5, 4.11, 4.19
4.5, 4.11, 4.19
4.2
4.5, 4.11, 4.19
4.12
4.12
4.12
4.12
4.12
4.12
4.5, 4.6
4.17,4.19
4.5
4.7
4.5
4.1, 4.5, 4.6
4.5
4.17
4.5, 4.16, 4.19
4.17, 4.19
4.5, 4.15, 4.16, 4.19
4.5, 4.16, 4.19
4.5, 4.15, 4.16, 4.19
4.5 , 4.15
4.5 , 4.16, 4.19
4.15, 4.16, 4.19
4.3
4.4
4.5, 4.14
4.5
4.5
4.5, 4.6, 4.19
4.7
4.5
4.5
4.5, 4.19
4.1
4.8
4.13
4.18
Rate performance only.
4.9
4.5
4.10
4.2
Apr. 2008
Element
Group
Element Name6,7,8
Unit for
Quantity1,2,3, 4
Sq.m.
Sq.m.
Sq.m.
m10
All
Sq.m.
Sq.m.
Sq.m.
Sq.m.
Each
Sq.m.
Sq.m.
Caps
Shafts/columns/Pile Bents
Retaining walls Barrier Systems on walls
Railing Systems
Drainage Systems
Walls
Sidewalks/curbs Curbs
Sidewalks and medians
Trusses/Arches Bottom chords
Connections
Top chords
Verticals/diagonals
Notes:
Applicable Condition State Table Number 5
4.5, 4.11, 4.16, 4.19
4.5, 4.11, 4.16, 4.19
4.5, 4.17, 4.19
4.17, 4.19
4.7
4.5
4.5
4.5
4.5, 4.16, 4.19
4.16, 4.19
4.5, 4.16, 4.19
4.5, 4.16, 4.19
1 – For “All”, place the entire component (100%) in one condition state.
2 – For “Each”, give the number of occurrences of the component in each state.
3 – For cracks in concrete, estimate repair area (4m of crack = 1 sq. m of repair).
4 – For cracks in steel, estimate required repair area.
5 – Tables given are typical for element. Use appropriate table for applicable material. (See Section 4).
6 – Sub-elements (End/Middle) to be used for the following elements at expansion joint locations: Deck Top, Girders, Inside
Boxes
Sub-elements (End/Intermediate) to be used for the following elements at expansion joint locations:: Floor Beams, Stringers,
Bracing and Diaphragms
Sub-elements (End/Interior/Exterior) to be used for Soffits
Sub-elements (Interior/Exterior) to be used for Barrier/Parapet Walls
7 – For an explanation of which bridge components are included in each element, see Table 3.1.
8 – Similar element types should be grouped together (e.g. I-girders, x-frames, etc.)
9 - Optional element. Not required for MTO use.
10- For these elements that are inspected by linear metre, a defect in the post shall be assumed to affect the tributary area for that
post.
2-9
Apr. 2008
Table 2.2: Element List for Each Bridge Type*
Element
Group
Abutments
Element Name
Abutment walls
Ballast walls
Bearings
Wingwalls
Bridge Mounted Sign Supports
Accessories
(Attachments and Electrical
Signs)
Noise Barriers
Other
Signs
Utilities
Approaches
Approach slabs
Barriers
Curb and gutters
Drainage System
Sidewalk/Curb
Wearing surface
Barriers
Interior/
Exterior (for
faces
of
barrier)
Hand Railings
Posts
Railing Systems
Beams / Main Diaphragms
Longitudinal
End
Elements
Intermediate
(MLE’s)
Floor beams
End
Intermediate
Girders
Inside boxes
X
X
X
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
X
X
X
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
X
X
X
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
Slab on
Boxgirder
(concrete)
X
X
X
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
?
?
X
?
?
X
?
?
X
?
?
X
X
X
X
?
X
X
X
?
Slab on
Sub-element Slab on I- Slab on IBox-girder
girder
girder
(steel)
(Concrete)
(Steel)
Posttensioned
deck (rect.
voids)
Posttensioned
deck
Solid
Slab
Truss
Culvert Rigid
Frame
(circ. voids)
X
X
X
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
X
X
X
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
X
X
X
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
X
X
X
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
X
?
?
?
?
?
X or
X
?
?
?
?
?
?
X
?
?
X
?
X
X or
?
?
X
?
?
X
?
?
X
?
?
X
?
?
X
?
?
X
X
?
?
?
?
?
?
X
X
X or
X or
X or
End / Middle X (only with X
(only X (only with
exp. Joints) with exp. exp. Joints)
Joints)
X or
2-10
X or
X
(only
with exp.
Joints)
X or
X or
Apr. 2008
Element
Group
Element Name
PostSlab on
Posttensioned
Boxtensioned
deck (rect.
girder
deck
(circ. voids)
voids)
(concrete)
X (only with X
(only X (only with
exp. Joints) with exp. exp. Joints)
Joints)
Slab on
girder
girder
(steel)
(Concrete)
(Steel)
End/Middle
Stringers
Bracing
Coatings
End
Intermediate
End
Intermediate
Barrier Systems / Hand
Railings
Structural Steel
?
End/Middle
Culverts
Decks
Barrels
Inlet Components
Outlet Components
Deck Top
Drainage System
?
?
X
(Not
applicable for
ACR steel) or
X
(Not
applicable for
ACR steel) or
X (only with
exp. Joints)
X (only with
exp. Joints)
X
?
X
?
X
?
X or
X (only with
exp. Joints)
End / Middle
?
X
?
X or
X
(only
with exp.
Joints)
(Post-tensioned decks and End
Rigid Frames)
(Slab on I or Box Girders)
Solid
Slab
Exterior
Interior
End
Exterior
Interior
Truss
Culvert Rigid
Frame
?
X
X
X
X
?
X
X
?
?
X or
X (only with
exp. Joints)
X
?
X (Not X (Not
applicable applicabl
for
for ACR e
steel) or ACR
steel) or
X (only X (only
with exp. with exp.
Joints)
Joints)
X
X
X
X
X
?
?
X (only with X
(only
exp. Joints)
with exp.
Joints)
X
X
X
X
X (only
with exp.
Joints)
X
X
?
?
?
?
X
X (only with X
(only
exp. Joints) with exp.
Joints)
X
X
X
X
X (only with X
(only
exp. Joints) with exp.
Joints)
X
X
X
X
2-11
X
X
X (only
with exp.
Joints)
?
X
Apr. 2008
Element
Group
Embankments
and Streams
Foundations
Joints
Piers
(only for multispan structures)
Retaining walls
Sidewalks/curbs
Trusses/Arches
Notes:
*
X
X or
?
Element Name
Slab on
Boxgirder
(concrete)
X
X
X
X
X
X
X
X
X
X
X
X
? (only for ? (only for ? (only for ? (only for
water
water
water
water
crossing)
crossing) crossing)
crossing)
X
X
X
X
Posttensioned
deck (rect.
voids)
Slab on
girder
girder
(steel)
(Concrete)
(Steel)
Wearing Surface
Embankments
Slope protection
Streams and Waterways
Foundation (below ground
level)
Armouring / retaining
devices
Concrete end dams
Seals / sealants
Bearings
Caps
Shafts/Columns/Pile
Bents
Barrier Systems on Walls Interior /
Exterior ( for
faces
of
barrier)
Walls
Curbs
Bottom Chords
Connections
Top chords
Verticals / Diagonals
X
X
X
? (only for
water crossing)
Posttensioned
deck
Solid
Slab
Truss
Culvert Rigid
Frame
(circ. voids)
X
X
X
X
? (only for
water
crossing)
X
X
X
X
X
X
X
? (only ? (only
for water for water
crossing) crossing)
X
X
X
X
X
X
X
X
X
X
? (only for
water
crossing)
X
?
?
?
?
?
?
?
X
?
?
X
?
X
?
?
X
?
X
?
?
X
?
X
?
?
X
?
X
?
?
?
?
X
?
?
?
?
X
?
?
?
?
X
X
X
X
?
X
X
?
X
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
X
X
X
X
?
?
?
?
= It should be noted that this list is for guidance only. The actual element list should be customised to suit the structure being inspected.
= Element Required
= Element or subsequent element must be chosen (only 1 of the choices needs to be selected) e.g. Barrier /parapet wall or Railing System
= May be applicable if component exists (e.g. Exp. Joint)
2-12
Apr. 2008
SECTION 3 – ELEMENT QUANTITY CALCULATIONS
As described earlier, this version of the Ontario Structure Inspection Manual is based on the “severity and
extent” philosophy. In order to estimate rehabilitation needs, quantities of material defects in each Condition
State must be recorded for each element. To determine the most suitable rehabilitation option, the recorded
defect quantity must be compared to the overall quantity for that element. The Structure Rehabilitation Manual
describes how to select the appropriate rehabilitation option based on the extent of material defects.
Table 3.1 describes how to calculate dimensions (length, width, height) and quantities for the various types of
elements. In general, dimensions can be obtained from structural drawings, however, these values should be
verified in the field (e.g. curb height may have been reduced after a resurfacing operation). It should be noted
that the quantity calculation is approximate in some cases (e.g. surface area of a girder), but is accurate enough
to be used in estimating rehabilitation needs. In general, quantities are calculated for one element (e.g. girder)
and then the Total Quantity is calculated by multiplying the quantity by the number of that type of element
(Count).
In an effort to simplify the inspection process, the parts of the structure that are likely to be in similar condition
are grouped together. This is accomplished by using “sub-elements”, as described in Section 2. When subelements are used, element quantities shall be calculated for each sub-element, as described in Table 3.1 and
Figures 3.1 – 3.4.
For elements that are partially buried, quantities should be calculated for the part of the element that is visible
above the ground (e.g. pile bents). For all other elements, the quantity shall be based on the total area of the
element as shown on the plans. (e.g. ballast wall). When inspecting an element that is partially hidden (e.g.
ballast wall), the quantity of material defects should be estimated based on the portion that is visible. For
example, a ballast wall at an expansion joint location may show signs of severe defects if the expansion joint has
been leaking. If the visible part of the wall is in “Poor” Condition, the inspector can probably assume that the
remainder of the wall is in similar condition.
2-13
Oct. 2000
Table 3.1: Procedures for Computing Element Dimensions and Quantities
Element Group
Element Name
Abutments
Abutment walls
Width (m)
average width of
abutment from
wing wall to
wing wall
Ballast walls
N/A
average width
wing wall to
wing wall
Bearings
N/A
N/A
Wingwalls
average length N/A
of wing walls
(from 6 bearing
to end of
approach)
N/A
N/A
Average height
Total # of
bearings at
abutments
# of wingwalls
N/A
# of Accessories Count (Each)
N/A
Average length
N/A
N/A
N/A
Height
# walls (typ. 2) Count x Length (m)
N/A
N/A
N/A
N/A
N/A
N/A
Sign
Height (m)
Average top of
bearing seat
elevation –
average top of
ground elevation
+ bearing seat
width + visible
part of footing
For Decks
without exp.
Joints
Average
underside of deck
soffit elevation –
average bearing
seat elevation
For Decks with
exp. joints
Top of deck
elevation –
average bearing
seat elevation
N/A
Count
# of abutments
(2 max.)
Quantity (Sq.m)1
Comments
width x height x Includes bearing seat
count
width and top of footing (if
visible).
Length (m)
N/A
Bridge
Mounted
Accessories
Supports
(Attachments and
Electrical
Signs)
Noise Barriers
Sub-element
# of ballast walls width x height x
count
Quantity includes entire
ballast wall even if some
areas are not visible due to
diaphragms.
count
(Units are Each)
length x height x
count
(including approach)
Other
Signs
Utilities
N/A
N/A
N/A
2-14
Apr.2008
Length (m)
Approach slab
length
Length of
Barrier
avg. length of
approach slab
Width (m)
curb to curb
width
Height (m)
Thickness
Count
Quantity (Sq.m)1
# of approaches count x width x
length
N/A
Min. height of
curb
Drainage System
N/A
N/A
N/A
Sidewalk/Curb
avg. Length of
approach slab
Approach slab
length
total length
including
approaches (to
end of approach
slabs) for one
side
avg. width of
sidewalk
curb to curb
width
Thickness at top
Min. height of
sidewalk curb
Thickness
# of curbs (2 per count x length
(units are m)
abutment
maximum)
N/A
Count (typ.)
Units are Each
# of sidewalks count x length x
(width + height)
# of approaches count x width x
length
# of sides
length x height* x
(typically 2)
count
total length of
railing on top of
barrier (includes
approaches) on
one side
Length
dimension of a
post along
length of bridge
N/A
N/A
Element Group
Element Name
Approaches6
Approach slabs
Sub-element
Barrier
Curb and gutters
Wearing surface
Barriers
Hand Railings
Posts
Railing Systems
Interior /
Exterior ( for
faces of
barrier)
Barrier height
width of post in Height of posts
transverse
direction
length of 1 steel N/A
panel
# of sides
count x length
(units are m)
# of posts
Count
(units are Each)
Height of barrier # of panels
2-15
length x count
(units are m)
Comments
General drainage at each
corner of the bridge.
Sub-elements must be used
and interior and exterior of
barrier/parapet must be
rated separately. * include barrier top with
interior. This element is
also used for concrete end
posts.
This element is to be used
for railings on top of
barrier/parapet walls.
for the post component of
open type railing systems.
(Posts of Wood, Steel,
Concrete, etc).
for open type of railing
systems (steel railing, flex
beam, etc)
Apr.2008
Element Group
Element Name
Diaphragms
Beams / Main
Longitudinal
Elements
(MLE’s)
Sub-element
End2
Intermediate
Floor beams
Length (m)
Width (m)
Height (m)
girder spacing or average width of Depth of section
for cross or “K” flanges
bracing: total
length of all
bracing members
measured along
the length of the
member
Count
# of individual
diaphragm
segments
Quantity (Sq.m)1
Count
(Units are Each)
or
For concrete use
length x count x
(height x 2 +
width)
average width of Depth of section
flanges
# of individual
diaphragm
segments
Count
(Units are Each)
or
For concrete use
length x count x
(height x 2 +
width)
average width of Depth of section
flanges
# of individual
members
(braces)
Count
(Units are Each)
or
For concrete use
length x count x
(height x 2 +
width)
All diaphragms in the
span(s).
average width of Girder depth
# of beams
flanges (simple (flange to flange)
avg.)
length x count x
(height x 2 +
width x 3)
Girder depth
# of beams
(flange to flange)
length x count x
(height x 2 +
width x 3)
length x count x
(height x 2 +
width x 3)
All floor beams. To be
used if all floor beams are
of the same type and the
deck does not have
expansion joints.
(See Figure 3.1c)
End floor beams at
expansion joint locations.
(See Figure 3.1c)
Intermediate floor beams
(See Figure 3.1c)
girder spacing or
for cross or “K”
bracing: total
length of all
bracing
members
measured along
the length of the
member
girder spacing or
for cross or “K”
bracing: total
length of all
bracing
members
measured along
the length of the
member
curb to curb
width
End
curb to curb
width
Intermediate
curb to curb
width
average width of
flanges (simple
avg.)
average width of
flanges (simple
avg.)
2-16
Girder depth
# of beams
(flange to flange)
Comments
All Diaphragms on bridges
with no expansion joints.
To be used if all
diaphragms are of the
similar type and the deck
does not have expansion
joints. End sub-elements
are not required.
(See Figure 3.1b)
Diaphragms at support
locations with expansion
joints (piers, abutments).
Similar diaphragm types
should be grouped
together. End sub-elements
are required.
(See Figure 3.1b)
Apr.2008
Element Group
Element Name
Girders
Sub-element
End
Middle
Inside boxes
End
Middle
Stringers
Height (m)
Count
Quantity (Sq.m)1
Girder depth
# of lines of
For I girders:
(flange to flange) girders or boxes length x count x
(height x 2 +
width x 3)
For Boxes:
length x count x
(height x2+width)
Girder depth
# of lines of
For I girders:
(flange to flange) girders or boxes length x count x
(height x 2 +
width x 3)
For Boxes:
length x count x
(height x 2 +
width)
Girder depth
# of lines of
For I girders:
Sum of span
For I girders:
lengths + sum of average width of (flange to flange) girders or boxes length x count x
(height x 2 +
overhangs – sum flanges (simple
avg.)
width x 3)
of “Ends”
For Boxes:
For Boxes:
bottom flange
length x count x
width
(height x 2 +
width)
bottom flange
Girder depth
# of lines of
length x count x
total length
width
(flange to flange) boxes
(height x 2 +
(spans +
width)
overhangs)
Girder depth
# of lines of
length x count x
Range 1 to 3 m, bottom flange
(height x 2 +
with default of width
width)
2m. Inspector
has option to
choose a length
between 1 to 3
m.
bottom flange
Girder depth
# of lines of
length x count x
Sum of span
(height x 2 +
lengths + sum of width
width)
overhangs – sum
of “Ends”
floor beam
average width of Depth
# of stringers
count
spacing
flanges
(Units are Each)
Length (m)
total length
(spans +
overhangs3)
Width (m)
For I girders:
average width of
flanges (simple
avg.)
For Boxes:
bottom flange
width
Range 1 to 3 m, For I girders:
with default of average width of
2m. Inspector flanges (simple
has option to
avg.)
choose a length For Boxes:
between 1 to 3 bottom flange
m.
width
2-17
Comments
Entire length of girders.
To be used if the deck does
not have expansion joints.
(See Figure 3.1a)
For decks with expansion
joints.
(See Figure 3.1a)
To be used in areas away
from expansion joints in
conjunction with the “end”
element.
(See Figure 3.1a)
Entire length to be used if
deck does not have
expansion joints.
joints.
element. (See Figure 3.1a)
All stringers. To be used if
the deck does not have
expansion joints.
Apr.2008
Element Group
Bracing
Element Name
Width (m)
Spacing of
stringer sets
End
floor beam
spacing
flanges
Intermediate
floor beam
spacing
average length
of 1 bracing
member
flanges
N/A
N/A
End
average length
of 1 bracing
member
average length
of 1 bracing
member
N/A
N/A
N/A
# of bracing
members
Count
(Units are Each)
Bracings in end panel.
(See Figure 3.1b)
N/A
N/A
# of bracing
members
Count
(Units are Each)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Use Area of
corresponding
Barrier System
element
Use Area of
corresponding
element such as
girder, floor
beams etc.
Use Area of
corresponding
sub-element such
as end of girder,
end floor beams
etc.
Bracings in Intermediate
panel
(See Figure 3.1b)
If the element units are not
sq. m., obtain appropriate
area.
Bracing
Intermediate
Coatings
Barrier Systems / Hand
Railings
Structural Steel
End
2-18
Height (m)
Stringer depth
Count
Quantity (Sq.m)1
Comments
# stringer set
count
Stringer sets often span
wide x # stringer (Units are Each) over a transom. Ramp at
sets long
bridge ends is an approach
slab and not a stringer.
# of stringers
count
Stringers in end panel at
(Units are Each) exp. joint locations
(See Figure 3.1c)
# of stringers
Count
Stringers in intermediate
(Units are Each) panels
# of bracing
Count
All Bracings - includes
members
(Units are Each) bracing between trusses
and lateral bracing
between floor system in
horizontal plane - vertical
plane is considered a
diaphragm element
(See Figure 3.1b)
Sub-element
Length (m)
(For Modular Length of
Bridges)
stringer sets
For all structural steel.
To be used if the
corresponding element
used “End” elements.
Apr.2008
Element Group
Culverts5
Decks
Element Name
Sub-element
Length (m)
Middle
N/A
Width (m)
N/A
Height (m)
N/A
Count
N/A
Quantity (Sq.m)1
Use Area of
corresponding
sub-element such
as middle of
girder, end floor
beams etc.
total interior
surface area for
one cell x # of
cells
area of all inlet
components
Barrels
total length of
culvert
Average cell
width
Height of cell
# of cells
Inlet Components
N/A
N/A
N/A
1
Outlet Components
N/A
N/A
N/A
1
area of all outlet
components
Deck Top
sum of span
overall width
lengths + sum of (out-to-out)
overhangs3
N/A
N/A
Deck thickness
minimum
N/A
length x width
N/A
N/A
Count
(units are Each)
sum of span
Sum of distance N/A
lengths + sum of between top
overhangs3
flanges inside of
boxes (steel or
concrete)
Range 1 to 3 m, Sum of distance N/A
with default of between top
2m. Inspector flanges of boxes
(steel or
has option to
choose a length concrete)
between 1 to 3
m.
Sum of span
Sum of distance N/A
lengths + sum of between top
overhangs – sum flanges of boxes
of “Ends”
(steel or
concrete)
N/A
length x width
N/A
length x width
N/A
length x width
Drainage System
End
Middle
2-19
Comments
To be used if the
corresponding element
used “Middle” elements
Interior surface area
includes soffit, walls and
bottom slab of culvert if
present
Includes all components.
( head walls, cut-off walls,
aprons, etc)
Includes all components.
( head walls, cut-off walls,
aprons, etc)
(See Figure 3.2b)
Includes all components
such as drains, drain pipes,
connecting pipes, etc. Can
also be per side of bridge
The entire soffit length
inside the boxes. To be
used for decks without
expansion joints
(See Figure 3.2c)
joints
(See Figure 3.2c)
element. (See Figure 3.2c).
Apr.2008
Element Group
Element Name
(Post-tensioned decks
and Rigid Frames)
(Slab on I or Box
Girders)
Sub-element
Length (m)
End
Range 1 to 3 m,
with default of
2m. Inspector
has option to
choose a length
between 1 to 3
m.
Exterior
Sum of span
lengths + sum of
overhangs – sum
of “Ends”
Width (m)
overall width +
fascias
Height (m)
N/A
N/A
Quantity (Sq.m)1
Comments
length x width
joints
fascias +
cantilevers4
N/A
N/A
length x width
N/A
N/A
length x width
fascias + exterior N/A
cantilevers to
flanges + sum of
distances between
flanges (for boxes
use outside of box
top flanges only)
N/A
length x width
fascias + exterior N/A
cantilevers to
flanges
N/A
length x width
Interior
overall width –
Sum of span
lengths + sum of cantilevers4
overhangs – sum
of “Ends”
End
Range 1 to 3 m,
with default of
2m. Inspector
has option to
choose a length
between 1 to 3
m.
Sum of span
lengths + sum of
overhangs – sum
of “Ends”
Exterior
2-20
Count
For Rigid frames, span
lengths are from faces of
abutments and piers and
the cantilever is assumed
to be 1m as shown in
Figure 3.4.
When End elements are
used, the length will be
reduced by the sum of the
End elements.
(See Figure 3.2c)
For Rigid frames, span
lengths are from faces of
abutments and piers.
End elements.
(See Figure 3.2c)
joints
End elements.
Apr.2008
Element Group
Element Name
Wearing Surface
Embankments &
Streams
Foundations
Joints
Piers
Sub-element
Length (m)
Interior
Sum of span
lengths + sum of
overhangs – sum
of “Ends”
Width (m)
Height (m)
sum of distances N/A
between flanges
(for boxes use
outside of box
top flanges only)
Count
N/A
Quantity (Sq.m)1
Comments
length x width
End elements.
Roadway width Thickness of
(curb to curb)
wearing surface
from drawings
N/A
N/A
N/A
length x width
Embankments
Sum of span
lengths + Sum
of overhangs
N/A
N/A
Units are Each
Slope protection
N/A
N/A
N/A
N/A
Units are Each
Streams and
Waterways
Foundation (below
ground level)
N/A
N/A
N/A
N/A
Units are All
N/A
N/A
N/A
N/A
N/A
Armouring / retaining
devices
Overall width
N/A
(out-to-out) for 1
armouring
Concrete end dams
Curb to curb
width
Seals / sealants
Overall width of N/A
bridge (for 1
seal)
N/A
N/A
Bearings
N/A
width of one side N/A
only
N/A
N/A
2-21
# of armourings
(Typically, 2 per
joint x # of
joints)
# of end dams (2
per joint x # of
joints)
# of seals
count x length
(units are m)
A typical abutment has 3
embankments (1 at front face
and 2 side slopes).
A typical abutment has 3
slopes (1 at front face and 2
side slopes).
Foundation is considered
to be anything below
ground.
This element is rated for
performance only and not
material condition.
If top of footing is visible,
it should be rated under the
Abutment wall or Pier
Shaft element.
For multi-seal joints, the
total length shall include
the armouring, separator
beams, support beams, etc.
length x width x
count
count
(units are Each)
Total # of
count
bearings at piers (Units are Each)
Apr.2008
Element Group
Element Name
Caps
Sub-element
Shafts/Columns/Pile
Bents
Retaining walls
Barrier Systems on
Walls
Walls
Sidewalks/curbs
Curbs
Interior /
Exterior ( for
faces of
barrier)
Quantity (Sq.m)1
count x 2 x
[(width x height)
+ (length x
height) + (length
x width)]
# of shafts or # For Rectangular
For Rectangular For rectangular Bearing seat
of columns or # Shafts or
elevation or
Shaft or
Shaft or
of piles
elevation at
Column:
Columns:
Column:
2 x (length +
bottom of pier
avg. width of
Thickness
width) x height x
parallel to bridge shaft or column cap - top of
count
ground elevation
For Round
length
For Round
Columns , Pipe (if under water
For Round
Columns , Pipe Piles or Timber use stream bed
Columns, Pipe
elevation)+
Piles or Timber Piles:
Piles or Timber
bearing seat
Diameter
Piles:
Piles:
width+visible part
For H-Piles:
Diameter
Β x width x
of footing
For H-Pile
flange width
height x count
Bents:
For H Piles:
web heights
count x height x
(2 x length + 4 x
width)
N/A
Barrier height
# of sides
length x height x
total length
(typically 2)
count
including
approaches (to
end of approach
slabs) for one
side
average length N/A
Average height of # of walls
length x height x
of wall
wall
count
length x ( width +
total length of
avg. width of all Maximum height # of curbs
height) x count
bridge excluding curbs
(need to verify in
approaches
field because of
resurfacing)
avg. width of all Maximum height # of sidewalks / length x ( width +
total length of
height) x count
(need to verify in medians
bridge excluding sidewalks /
field because of
medians
approaches
resurfacing)
Length (m)
Width (m)
width of cap
Thickness or
length of caps
parallel to length
of bridge
2-22
Height (m)
Depth or height
of cap
Count
# of caps
Comments
Note: similar shapes
should be combined as an
element
Includes bearing seat
width and top of footing (if
visible).
Sub-elements must be used
and interior and exterior of
barrier/parapet must be
rated separately.
See Figure 3.3 for
definition of sidewalk /
median and curb
See Figure 3.3 for
definition of sidewalk /
median and curb
Apr.2008
Element Group
Element Name
Trusses/Arches
Bottom Chords
Sub-element
Length (m)
total length of
top chord (all
panels)
Width (m)
average flange
width
Height (m)
Depth of section
Count
Quantity (Sq.m)1
# of chords/side For I Sections:
= 2 usually
quantity = count x
length x(height x
2 + 4 x width)
Comments
For T or L Sections:
quantity = count x
length x (height x
2 + 2 x width)
Connections
N/A
N/A
N/A
# of connections Count
Main truss connections7
(Units are Each)
Top chords
total length of
average flange Depth of section # of chords/side For I Sections:
top chord (all
width
= 2 usually
quantity = count x
panels)
length x (height x
2 + 4 x width)
For T or L
Sections: quantity
= count x length x
(height x 2 + 2 x
width)
Verticals / Diagonals
average length average flange Depth of section # of verticals / For I Sections:
of diagonals
width
diagonals for all quantity = count x
sides
length x (height x
2 + 4 x width)
For T or L
Sections:
quantity = count x
length x (height x
2 + 2 x width)
Notes: 1 – Default units are sq.m unless noted otherwise.
2 – End elements are to be used at all expansion joint locations
3 – Overhang = Distance from centre of Bearing to end of deck (See Figure 3.1a, 3.2a) 4 – For definition of Cantilever, See Figure 3.4
5 – Culverts include soil-steel structures.
6 – The length of the “approach” should be taken as the length of the approach slab or the length to the end of the wingwalls (whichever is greater). For
modular bridges, the ramps are taken as approaches.
7 – For Modular bridges, a separate connection occurs for the top and bottom chord, but all panels wide plus chord reinforcement is part of 1 connection.
2-23
Apr.2008
(a) Girders (Elevation view)
(b) Girders, Diaphragms and Bracing (Plan view)
(c) Floor Beams and Stringers
Figure 3.1: Structural Steel Definitions
2-24
Oct. 2000
(a)
Deck (Elevation view)
(b) Deck Top
(c)
Deck Soffit
Figure 3.2: Deck Definitions
2-25
Oct. 2000
Figure 3.3: Curb and Sidewalk Definitions
2-26
Oct. 2000
Figure 3.4: Cantilever Definitions
2-27
Oct. 2000
SECTION 4 – MATERIAL CONDITION STATE TABLES
In general, Material Condition States are used to categorize the condition of an element based on the severity of
material defects. Four Material Condition States have been defined for bridge elements, namely, Excellent, Good, Fair
and Poor. The condition of bridge elements is defined to be in any one or more of these Condition States. At any given
time, areas within a bridge element may be in different Condition States, or the whole of the element may be in the
same Condition State. For each bridge element, the inspector assesses and records the amount (area, length or unit, as
appropriate) of the element in each of the four Condition States. This assessment is based predominately on visual
observations, however, some non-destructive testing, such as hammer tapping of concrete for delamination, will be
required to determine or verify areas in poor condition. Where an area in poor condition is noted, the area is to be
measured (if practicable), or estimated.
In some cases, an exceptionally poor localized zone in a critical element may render the entire element ineffective. For
such cases, the particular element can be considered to be 100% Poor and immediate action must be taken. This
includes notifying the owner to initiate temporary repairs and a strength evaluation. Examples of this include:
- A truss member where perforation corrosion at one location (i.e. near a gusset or passing through a sidewalk)
will result in the length between panel points being rated as Poor.
- A corrugated steel pipe where perforation corrosion at one location (i.e. bottom or waterline) will result in the
entire circumferential band being rated as Poor.
- A timber pile where damage (decay, ice damage, etc.) that greatly reduces the capacity, but occurs in a small
zone (i.e. the waterline) will result in that pile being rated as Poor.
If any element has been repaired so that the capacity has been fully restored, the condition of the repair should be rated
and not the original material. If the repair is of a temporary nature, but does substantially restore the element
effectiveness (capacity), then only the portion of the element in Poor condition is rated as such.
The importance of recording quantities of defects cannot be over-emphasized. Using rough percentages without some
sort of verification will usually lead to a grossly inaccurate estimation of rehabilitation needs. This is especially true in
the “Poor” Condition State. Although the extent of defects is still based on visual observations, studies have shown that
the recording of actual quantities (square metre or metre) leads to a better estimation of rehabilitation needs.
There are four basic units that are used to describe the material condition of various elements (See Table 2.1):
• SQUARE METRE (Area): For many elements, the condition states will be recorded as an area
measurement, m2. For example, a deck element of area 1000 m2 may have 100 m2 in excellent condition,
700 m2 in good condition, 100 m2 in fair condition and 100 m2 in poor condition.
• LINEAR METRE (Length): For some elements, such as the expansion joint armouring, the data is recorded
by linear metre. For example, an expansion joint armouring of 10 m length may have 0 metres in excellent
condition, 3 metres in good condition, 2 metres in fair condition, and 5 metres in poor condition.
• EACH: For some elements, such as bearings, the unit is “each”. For example, a bridge with 10 bearings
may have 5 bearings in excellent condition, 3 bearings good condition, 1 bearing in fair condition and 1
bearing in poor condition.
• ALL: For some elements, the entire element is placed completely into one condition state as described in the
appropriate condition state table (e.g. streams and waterways).
Condition State tables (See Tables 4.1–4.19) have been created for each material type (e.g. steel, concrete) and, where
required, for specialized elements (e.g. bearings, expansion joint seals, etc). The Condition State that an element is in
is defined by the severity of the defect(s) that exist in that element. All material defects are defined in Part 1, Section
2 of this manual. In general, the severity of a defect is defined by the terms “Light, Medium, Severe and Very
Severe”. The definitions of these severity terms are also contained in Part 1, Section 2 for each type of defect.
Appendix A to Part 2 contains Tables with an amalgamation of the information in Part 1, Section 2 and this Section.
As a general rule of thumb, the following philosophy is used for most condition state tables:
(i) Excellent
• This refers to an element (or part of an element) that is in “new” (as constructed) condition
• No visible deterioration type defects are present and remedial action is not required.
• Minor construction defects do not count as visible deterioration type defects.
• Examples:
•
“bug holes” in concrete barrier walls
• well-formed patina in atmospheric corrosion resistant(ACR) steel girders
2-28
Apr. 2008
Nov. 2003 Revision
(ii)
Good
• This refers to an element (or part of an element) where the first sign of “Light” (minor) defects are
visible. This usually occurs after the structure has been in service for a number of years. These types
of defects would not normally trigger any remedial action since the overall performance of the element
is not affected.
• Examples:
• Light corrosion (no section loss)
• Narrow cracks in concrete
• Light scaling
• Light decay in wood
(iii) Fair
• This refers to an element (or part of an element) where medium defects are visible. These types of
defects may trigger a “preventative maintenance” type of remedial action (e.g. sealing, coating, etc)
where it is economical to do so.
• Examples:
• Medium corrosion (up to 10% section loss)
• Medium cracks in concrete
(iv)
Poor
• This refers to an element (or part of an element) where severe and very severe defects are visible. In
concrete, any type of spalling or delamination would be considered “poor” since these defects usually
indicate more serious underlying problems in the material (e.g. corroding reinforcing steel). These
types of defects would normally trigger rehabilitation or replacement if the extent and location affect
the overall performance of that element.
• Examples:
• Severe corrosion (Greater than 10% section loss)
• Spalling, delaminations, etc
For a typical inspection, the “Poor” areas of each element are identified first. Generally, each area of “Poor”
also has an area in the “Fair” Condition State surrounding it. This area is usually, as a minimum, equal to the
area of “Poor” for small quantities of “Poor”, while for larger quantities of “Poor” a smaller percentage of the
area can be used. There are also separate areas in the “Fair” Condition State that are to be included. The
remainder of the areas are in either “Good” or “Excellent” Condition.
For most elements, a general progression through the various condition states occurs over time. The difference
between The “Excellent” and “Good” condition states is not always obvious from a distance. However, minor
defects can be detected upon close visual inspection of elements more than 5 years old (depending on the
exposure environment). The following general guidelines may be used by the inspector to supplement visual
inspection data to determine when an element (concrete, ACR steel, Coated Steel, or Coating) should progress
from “Excellent” to “Good”:
(i)
Severe Environment – 5 years to become Good
(ii)
Moderate Environment – 15 years to become Good
(iii)
Benign Environment – 25 years to become Good
For a few inspections prior to the timelines listed above, proportions of the element in both “Excellent” and
“Good” may be used to ensure a smooth transition from “Excellent” and “Good”.
The presence of material defects usually triggers further, more detailed investigations. The most common types
of investigations are for concrete elements (e.g. Bridge Deck Condition Survey, Substructure Condition Survey,
etc). Investigations can also be done for other materials such as steel, wood, etc. Additional investigations are
usually triggered when a pre-determined percentage is exceeded in the “poor” Condition State. Tables 4.1 to
4.19 list these triggers. In some cases, the first sign of a material defect would trigger a more detailed
investigation. An example would be a fatigue crack in a steel girder, which would trigger an immediate fatigue
investigation. Part 3 of this manual describes some of the additional investigations that can be done.
In addition, material defects often lead to performance deficiencies, which would trigger other follow-up actions,
such as a strength evaluation. Performance deficiencies and corresponding follow-up actions are described in
Section 5.
2-29
Apr. 2008
MATERIAL CONDITION STATE TABLES
Table #
Page
4.1
Asphalt Wearing Surface ............................................................................................................2-31
4.2
Bearings ......................................................................................................................................2-31
4.3
Coating - Steel Railings ..............................................................................................................2-32
4.4
Coating - Structural Steel Substructures and Superstructures.....................................................2-32
4.5
Concrete - Substructures and Superstructures.............................................................................2-34
4.6
Concrete - Top of Deck Beneath Asphalt Wearing Surface .......................................................2-35
4.7
Drainage System .........................................................................................................................2-35
4.8
Embankments..............................................................................................................................2-36
4.9
Expansion Joint - Armouring and Retaining Devices.................................................................2-36
4.10
Expansion Joint - Seals/Sealant ..................................................................................................2-36
4.11
Masonry Construction.................................................................................................................2-37
4.12
Accessories (Attachments and Signs) ........................................................................................2-37
4.13
Slope Protection ..........................................................................................................................2-37
4.14
Soil-Steel Structures....................................................................................................................2-37
4.15
Steel-Atmospheric Corrosion Resistant Substructures and Superstructures...............................2-38
4.16
Steel or Aluminum - Substructures and Superstructures ............................................................2-38
4.17
Steel or Aluminum- Railings ......................................................................................................2-38
4.18
Streams and Waterways ..............................................................................................................2-39
4.19
Wood - Substructures and Superstructures .................................................................................2-39
Apr. 2008
2-30
Nov. 2003 Revision
Table 4.1: Asphalt Wearing Surface
Excellent Condition
Good Condition
Fair Condition
Poor Condition
No Observed Material
Defects
Light cracking
Medium cracking
Light ravelling
Medium ravelling
Light Potholes
Medium Potholes
Light wheel track rutting
Light Rippling
Medium wheel track
rutting
Medium Rippling
Light Flushing
Medium Flushing
Severe to very severe
cracking
Severe and very severe
ravelling
All areas with loss of bond
potholes
wheel track rutting
Severe and Very Severe
Rippling
flushing
For all calculations, the actual area shall be determined for areas containing numerous cracks (i.e. alligator cracks, radial
cracks). For isolated cracks, 4 m of crack length is to equal to 1 square metre of defect repair area.
Table 4.2: Bearings
Excellent Condition
Good Condition
Fair Condition
Poor Condition
No Observed Material
Defects
Hairline cracks in
elastomeric pads
Very wide cracks in
elastomeric pads and/or steel
plates debonded
Severe bulging or shear
deformations in elastomeric
pads, or severe local
deformation of roller/rocker
plates
Light Corrosion
Narrow to medium
cracks in elastomeric
pads
Medium bulging or
shear deformations in
elastomeric pads, or
medium local
deformation of
roller/rocker plates
Medium
scoring/scratches in TFE
or stainless steel
Medium Corrosion
Anchor bolts slightly
bent
Guide bars and thrust
plates slightly worn
Anchor bolts severely
bent and cracked
Guide bars and thrust
plates moderately worn
Up to 5% of bonded
sliding surface is
debonded
5% to 20% of bonded
sliding surface is
debonded
Light bulging or shear
deformations in
elastomeric pads, or
light local deformation
of roller/rocker plates
Light scoring/scratches
in TFE or stainless steel
Severe scoring/scratches or
rips and tears in TFE or
stainless steel
corrosion and or cracks in
steel
Anchor bolts are broken
Guide bars and thrust plates
severely worn and/or loose
or missing nuts
Over 20% of bonded sliding
surface is debonded
Internally confined
compression material is
squeezing or squeezed out
2-31
Nov. 2003 Revision
Table 4.3: Coating* – Steel Railings
Excellent Condition
Good Condition
Fair Condition
Poor Condition
RUST
CONDITION**
RATING
CATEGORY 1
RUST
CONDITION
RATING
CATEGORY 2
RUST
CONDITION
RATING
CATEGORY 3
RUST
CONDITION
RATING
CATEGORY 4 or
higher
Table 4.4: Coating* - Structural Steel Substructures And Superstructures
Excellent Condition
Good Condition
Fair Condition
No Observed
Material Defects
Chalking
Checking, cracking,
alligatoring
Intercoat
delamination,
peeling (top coat
only)
Signs of chemical
attack
Bridging, edge
defects, shadows
RUST
CONDITION**
RATING
CATEGORY 3
RUST
CONDITION**
RATING
CATEGORY 1
Overspray, runs,
sags, pinholing
RUST
CONDITION**
RATING
CATEGORY 2
Poor Condition
Undercutting,
blisters, peeling
(prime coat),
underfilm corrosion
RUST
CONDITION**
RATING
CATEGORY 4 or
higher
Coating Condition Survey is required if
the combined area in the Fair and Poor
Condition States is greater than 25% and
the area in the Poor Condition State is less
than 10% ***
*
Galvanized elements are included under the “Coating” category
**
Rust Condition Ratings based on ASTM D 610 sketches are shown in Figure 4.1.
***
In order to consider overcoating as a viable rehabilitation option, a detailed condition
survey should be triggered before deterioration is too widespread. If the percentage in Poor
Condition exceeds 10%, overcoating is not a feasible treatment and a coating condition survey
is not required.
2-32
Apr.2008
Category 1: No Rust
Condition State: Excellent
Category 2: Light Surface Rust
Condition State: Good
Category 3: Medium Surface Rust
Condition State: Fair
Category 4: Severe Surface Rust
Condition State: Poor
Figure 4.1: Rust Condition Rating Categories for Coatings
2-33
Nov. 2003 Revision
Table 4.5: Concrete – Substructures and Superstructures
Excellent Condition
Good Condition
Fair Condition
Poor Condition
No observed material
defects
Light scaling
Medium scaling
Rust stains on
concrete due to
corroding rebar chairs
Surface carbonation
(Reaction with CO2 ,
associated
discolouration,
shrinkage and cracks)
Rust stains on concrete due
to corroding reinforcing
steel
Surface defects such as
stratification, segregation,
cold joints, abrasion, wear,
slippery surfaces, wet areas
and surface deposits (except
on soffits).
Medium honeycombing and
pop-outs
Medium cracks
Severe to very severe scaling,
erosion and disintegration
Medium to very severe
corrosion of reinforcing steel
Light honeycombing
and pop-outs
Hairline and Narrow
cracks
Light alkaliaggregate reaction
Medium alkali-aggregate
reaction
Stable relative displacement
between precast units.
Leaking between precast
units.
Severe to very severe
honeycombing and pop-outs
All wide cracks
Severe and very severe alkaliaggregate reaction
Active relative displacement
between precast units
All delaminated and spalled
areas
Active wet areas on soffit
without cracks
Active wet areas or leachate
deposits on soffit with
associated cracks
Condition Survey if area of
deterioration in this state
>10% for substructures
Deck Condition Survey if area
of deterioration in this state
>10% for superstructures
Notes:
(1) For all calculations, the actual area shall be determined for areas containing numerous
cracks (i.e. pattern cracks, map cracks). For isolated cracks, 4 m of crack length is to
equal to 1 square metre of defect repair area.
(2) If shear cracks are found at girder ends, an evaluation should be done. If cracks are wide,
the inspector should mark “URGENT” for the timeframe of the evaluation. As with other
potentially unsafe conditions, the bridge owner should be notified if these cracks are
noticed.
2-34
Nov. 2003 Revision
Table 4.6: Concrete - Top of Deck Beneath Asphalt Wearing Surface
Based on Visual Inspection of Asphalt
Excellent Condition
Good Condition
Fair Condition
No Asphalt Defects.
Top-Down Asphalt Defects
Light and medium isolated
cracks in asphalt.
Poor Condition
Bottom-Up Asphalt Defects
Local protrusions in
asphalt.
Wide isolated cracks in
asphalt.
(Cracks include:
longitudinal cracks, above
location of voids, edge of
beam flanges, joint
between precast units,
construction joints, etc., or
transverse cracks)
All Potholes in asphalt.
All Pattern cracking in asphalt
(e.g. map, alligator, radial, edge
cracking).
All Bond Defects (e.g.
rippling, loss of bond) in
asphalt.
All Surface Defects (e.g.
ravelling, flushing, slippery
surface) in asphalt.
All Surface Distortions
(wheel track rutting) in
asphalt.
Condition survey if the area of
deterioration in this state >10%
if not already done.
Notes:
(1) For all calculations, the actual area shall be determined for areas containing numerous cracks (i.e. alligator cracks,
radial cracks). For isolated cracks, 4 m of crack length is to equal to 1 square metre of defect repair area.
(2) If a bridge has been recently repaved without rehabilitating the deck, the inspector must estimate the condition of the
concrete deck using other means. This would include using previous inspection information, the age of the
waterproofing, deck condition survey data, etc.
Table 4.7: Drainage System
Excellent
Condition
No observed
material defects
Good Condition
Fair Condition
Poor Condition
Up to 20% of individual
drainage system has loose
or deteriorated components,
connections or fasteners
20% to 60% of individual
drainage system has loose or
deteriorated components,
connections or fasteners
More than 60% of individual drainage
system has loose or deteriorated
components, connections or fasteners
Broken pipe components resulting in
water draining onto substructure
2-35
Apr.2008
Table 4.8: Embankments
Excellent Condition
Good Condition
Fair Condition
Poor Condition
defects
Up to 10% loss of
material for
embankments not
directly supporting
foundations; or, up
to 5% loss for
embankments
directly supporting
foundations
10% - 30% loss of
material for
embankments not
directly supporting
foundations; or 5% to
15% loss for
embankments directly
supporting
foundations; or, loss of
material to the top of
foundations
More than 30% loss of
material for
embankments not
directly supporting
foundations; or, more
than 15% loss for
embankments directly
supporting foundations;
or, loss of material to
the bottom of
foundations
Table 4.9: Expansion Joint – Armouring and Retaining Devices
Excellent Condition
Good Condition
Fair Condition
Poor Condition
No observed
material defects
Light Corrosion*
Medium Corrosion*
Severe Corrosion*
Bolts, anchors,
armouring, clamping
devices or welds are
loose, broken or
missing.
* As defined in Table 4.16.
Table 4.10: Expansion Joint – Seals/Sealants
Excellent Condition
Good Condition
Fair Condition
No observed
material defects
Abrasions in seal
with no perforations
Loss of resiliency of
Cracks, tears or holes in
seal but no perforations the seal
Seal has debonded
Seal is allowing leakage
on the substructure.
Sealant debonded,
pulled out or settled.
2-36
Poor Condition
Oct. 2000
Table 4.11: Masonry Construction
Excellent Condition
Good Condition
Fair Condition
Poor Condition
defects
Hairline and narrow
cracks
Medium cracks
Wide cracks
Leaching of lime based
mortar
Light splitting, spalling
and disintegration
Light loss of pointing
mortar
Medium splitting, spalling
and disintegration
Medium loss of pointing
mortar
Severe and very severe splitting,
spalling and disintegration
Severe and very severe loss of
pointing mortar and stones
Table 4.12: Accessories (Attachments and Signs)
Excellent Condition
Good Condition
Fair Condition
Poor Condition
No observed defects
Not a standard sign
Not located according to
standards
Illegible
Gives misleading, wrong or
inaccurate information
Sign is missing
Light material defects
Medium material defects.
Loose, damaged or bent
components on attachment
Severe and very severe material
defects. Broken or missing
components on attachment
Table 4.13: Slope Protection
Excellent Condition
Good Condition
Fair Condition
Poor Condition
defects
Loss or deterioration of
less than 20% of slope
protection material
Loss or deterioration of 20%
to 60% of slope protection
material
Loss or deterioration of more
than 60% of slope protection
material
Table 4.14: Soil-Steel Structures*
Excellent Condition
Good Condition
defects
Light Corrosion (surface
rust).
* -
Fair Condition
Poor Condition
Medium Cusping or Crimping of
corrugations (less than 10 mm in
height)
Medium Global Deformation (less
than 10% of culvert diameter)
Bolt tilting
Severe Cusping or Crimping of
corrugations (greater than 10 mm
in height)
Severe Global Deformation
(greater than 10% of culvert
diameter or with reverse curvature)
Cracks
Medium Corrosion (Shallow pitting
and corrosion scale over surface –
less than 10% section loss)
Severe Corrosion (Deep pitting
and corrosion scale over surface –
greater than 10% section loss)
Unit of measure for soil-steel structures is m2. The area of defect should be recorded for Severe Corrosion (excluding
corrosion with perforations), as well as for the Excellent, Good and Fair Condition States. For all other portions in the
Poor Condition State (cusping, crimping, deformations, cracks and corrosion with perforations) the area shall be taken
to include the entire circumference. This is due to the importance of soil-steel interaction and continuity of the radial
corrugations of steel where such a defect at one point on the culvert will affect the entire circumference.
2-37
Apr.2008
Table 4.15: Steel – Atmospheric Corrosion Resistant Substructures and Superstructures
Excellent Condition
Good Condition
Fair Condition
Poor Condition
defects with smooth
uniform rust layer (patina)
Early signs of patina
flaking and no
section loss
Flaking and
delamination of Patina
up to 10% section loss
More than 10% section loss
Light connection
deficiencies
Medium connection
deficiencies
All cracks
Permanent deformations
Severe connection deficiencies
Evaluation and condition
survey* if > 10% in this state.
* Involves measuring thickness of critical members to determine section loss as it varies across the element.
Table 4.16: Steel or Aluminum – Substructures and Superstructures
Excellent Condition
Good Condition
Fair Condition
Poor Condition
defects
Light corrosion – no
section loss
Medium corrosion - up
to 10% section loss
Light connection
deficiencies
Medium connection
deficiencies
corrosion – more than 10%
section loss
All cracks (immediate action is
required -estimate repair area)
Evaluation and condition
survey* if > 10% in this state.
* Involves measuring thickness of critical members to determine section loss as it varies across the element.
Table 4.17: Steel or Aluminum - Railings
Excellent Condition
Good Condition
Fair Condition
Poor Condition
defects
Light corrosion – no
section loss
Medium corrosion - up
to 10% section loss
Slight loss of cable
tension or slight
slippage of cable
anchors and splices
Moderate loss of cable
tension or slight
slippage of cable
anchors and splices
corrosion – more than 10%
section loss
Significant loss of cable
tension or slight slippage of
cable anchors and splices
Broken cable strands/supports
Light connection
deficiencies
Medium connection
deficiencies
2-38
Collision or vandalism
damage/missing sections
Oct. 2000
Table 4.18: Streams and Waterways
Excellent Condition
Good Condition
Fair Condition
Poor Condition
No observed
material defects
A few locations of scour
or degradation of the
stream bed or stream
banks but not exposing
the foundations
Numerous locations of
scour or degradation of
the stream bed or stream
banks to the top of the
previously covered
foundations
Moderate scour at the
inlet or outlet of culverts
and soil-steel structures
Scour or degradation of the
stream bed or stream banks
to the bottom of previously
covered foundations
Slight scour at inlet or
outlet of culverts and
soil-steel structures
Stream alignment
shifted but not
encroaching against
components previously
not subject to stream
flow
A few locations of
aggradation not
affecting the stream
flow at the structure
Stream alignment
shifted and encroaching
close to components not
previously subject to
stream flow
Medium aggradation
having a significant
effect on the stream
flow at the structure
Extensive scour around the
inlet or outlet of culverts and
soil-steel structures with loss
of embankment fill
Stream alignment shifted
with stream flow directly
against most of a component
not previously subject to
stream
Extensive aggradation very
severely affecting the stream
flow at the structure)
Table 4.19: Wood – Substructures and Superstructures
Excellent Condition
Good Condition
Fair Condition
Poor Condition
defects
Light checks and shakes.*
Light weathering
Medium checks and
shakes.*
Medium weathering
Light rot or decay
Medium rot or decay
Light insect damage
Medium Insect Damage
Light abrasion and wear
Medium Abrasion and
wear
Medium cracking,
splintering, crushing and
shattering
Medium fire and chemical
damage
Medium connection
deficiencies
Severe and very severe checks,
and shakes and all splits.*
weathering
Severe and very severe rot or
decay.
Severe and very severe insect
damage
Severe and very severe abrasion
and wear
cracking, splintering, crushing
and shattering
Severe and very severe fire and
chemical damage
Light cracking, splintering,
crushing and shattering
Light fire and chemical
damage
Light connection
deficiencies
*-
Condition survey if area of
deterioration in this state > 10%
These naturally occurring cracks in the wood, caused by shrinkage, are not as severe as overload cracking or
splintering since wood fibres exist to bridge the crack and reduce the impact on the member capacity. The actual
area containing the defect shall be determined for areas containing numerous defects. For isolated cracks, 8 m of
crack length is equal to 1 square metre of defect for checks, shakes and splits; while 4 m of crack length is equal
to 1 square metre of defect for cracking, splintering, crushing and shattering. The length of cracks, shakes, splits,
etc. shall be measured on all surfaces.
2-39
Apr. 2008
Oct. 2000
SECTION 5 – SUSPECTED PERFORMANCE DEFICIENCIES
A Performance deficiency should be recorded if an element’s ability to perform its intended function is in
question, and one or more performance defects exist. Performance defects for the various elements of a structure
are described in Section 2, Part 1 of this manual. Often, an inspector “suspects” a performance deficiency, but is
unsure of the extent of this deficiency until some follow-up action is taken. A list of common performance
deficiencies is shown in Table 5.1. These deficiencies are often applicable to several elements, however, in some
cases, the deficiencies listed are applicable to only one type of element. An example of a suspected performance
deficiency is “Load Carrying Capacity”. The typical follow-up action for this deficiency would be to carry out a
strength evaluation of the structure (or element). Table 5.1 also describes typical deficiencies for various
elements, and lists possible follow-up actions. The follow-up action could take the form of either an additional
investigation or a maintenance operation.
In most cases, performance defects in an element are closely related to or attributable to material defects. In
some cases, performance defects exist due to defects in design or construction and may not be directly related to
material defects. Also, performance defects in a component may be the result of unexpected behaviour of the
structure or due to performance defects in other components of the structure.
It should be noted that the list of suspected performance deficiencies should be considered during the
inspection of each element.
2-40
Apr.2000
2008
Oct.
Table 5.1: Suspected Performance Deficiencies
1
Suspected
Performance
Deficiency
Element Name
(Examples)
Description of Deficiency
Possible Follow-up Action
Load Carrying
Capacity
Girder, Deck Top,
Railing System, etc
(Note –
deficiencies in
most elements can
trigger a strength
evaluation)
•
•
•
Strength evaluation
Monitoring of
deformations
(displacements or
rotations) or cracks.
•
•
Strength evaluation
Monitoring of
deformations
(displacements or
rotations)
•
Regular Monitoring of
settlement, pier and
abutment elevations and
crack widths
Strength evaluation
Geotechnical investigation
Underwater investigation
•
•
2
Excessive
Deformations
Railing System,
Deck Top, Truss
Chord,
Abutment Wall,
Bearings, etc
•
•
•
•
•
•
•
•
•
•
•
3
Continuing
settlement
Foundation
•
•
•
•
•
•
4
Continuing
Movements
Abutment Wall,
Pier, Deck Top,
Bearings, etc
•
Material defects leading to loss of
strength, or which are indicative of
inadequate strength of the component
(eg.20% section loss at mid-span of
girder)
Detrimental modifications made
subsequent to construction;
Strong evidence of under design for
current loads.
Severely bent members
Overloading, either single or repetitive
occurrence, resulting in permanent
deformations of the deck or deck
components.
Permanent deformations, especially in
compression components
Unanticipated or excessive vibration or
deflection of components, connections
or joints under live loads
Unexpected noise from components or
connections due to vehicles moving
across the structure.
Mis-alignment, lateral deformation,
warping, etc. of components;
Inability of the abutment to withstand
lateral earth pressures, as indicated by
long, medium horizontal cracks in
abutments;
Deformation of the roof slab, floor slab
or walls of culverts.
Deformation of soil-steel structures such
as flattening or peaking of the soffit or
buckling of the shoulders or haunches;
Up-lift at ends of soil-steel structures
Movements causing distress in a bearing
or it's components, or in other structure
components;
Loss of strength or support for applied
loads due to material defects;
Loss of material supporting foundations
due to scour or erosion
Consolidation or failure of underlying
soil resulting in cracking or movement
of foundations, abutments or piers
Loss of contact between piles and pile
cap or pier cap;
Changes in the inclination of piles.
Rotational movement of pile caps and
loss of full contact with piles.
Out of plumb of abutment walls, piles,
piers or other components supported on
them;
2-41
•
•
•
•
Regular monitoring and
measurement of
movements, inclinations,
Apr.
2008
Oct. 2000
Suspected
Performance
Deficiency
Element Name
(Examples)
•
•
•
•
•
•
•
•
•
Tilting or bulging of Retained Soil
System (RSS) walls
Unusual or unexpected substructure
movements occurring during the passage
of heavy vehicles over the bridge;
Tapering or misalignment of cracks and
joints in foundations, abutments, piers or
other components supported on them;
Sudden drops or kinks in the structure
profile over piers or abutment walls
when sighting along railings or beam
lines;
Abnormally large or small openings or
misalignment of deck expansion joints at
abutments and piers;
Abnormal displacements or inclinations
of bearings;
Abnormally large or small clearance
between ballast wall and superstructure;
Cracks in abutment wall and ballast wall
Shift in alignment from original
position;
5
Seized Bearings
Bearings
•
Binding or jamming of expansion or
rotational components due to corrosion,
lack of lubrication or damage to sliding
surfaces;
6
Bearing not
uniformly
loaded/unstable
Jammed
expansion Joint
Elastomeric
Bearing, Rocker
Bearing, etc
Armouring/
retaining devices
•
Non-uniform contact of bearing surfaces
with each other or with bearing seat
Excessive inclinations of bearings
Inadequate joint gap to accommodate
anticipated further movement;
Surfacing materials have jammed in the
joints during resurfacing of deck;
Design or construction problems not
allowing proper movement of multi-seal
joints.
7
•
•
•
•
8
Pedestrian/
vehicular hazard
Armouring/
retaining devices,
Sidewalk
•
•
•
•
9
Rough Riding
Surface
Wearing Surface,
Approach slabs
•
Vertical or horizontal misalignment
across the joint;
Severe material defects (e.g. Spalling)
Horizontal, vertical or rotational
displacements in curbs and sidewalks as
they are hazardous to pedestrian and
vehicular safety, and present
obstructions to snow plows.
Inadequate curb height, or loss of curb
height for sidewalks due to the
placement of an additional layer of
wearing surface or deck overlay
Rough approaches, settlement or
consolidation of approach embankments,
or deterioration of the approach slabs or
ramps, resulting in vehicles "bouncing"
2-42
•
•
crack widths, etc.
Underwater investigation
•
Strength evaluation to
account for change in
articulation
• Lubricate Bearings
(Maintenance Operation)
• Regular monitoring of
bearing movements
•
•
•
•
•
•
Regular monitoring of
deck movements
Clean out gap
(Maintenance operation)
Remove obstruction
(Maintenance operation)
Review Code requirements
for curb height
Smooth out asphalt at
approach (Maintenance
operation)
Strength evaluation
Oct. 2000
Suspected
Performance
Deficiency
Element Name
(Examples)
•
onto the bridge. In addition to applying
excessive dynamic loading to the bridge,
this may also result in difficulty in
maintaining vehicle control
Depressions and cracks in the roadway
pavement above culverts and soil-steel
structures;
10
Surface Ponding
Sidewalk,
Wearing surface
•
Water ponding on sidewalks/wearing
surface, as it presents a safety hazard,
especially if allowed to freeze;
•
Fill in depression with
asphalt (Maintenance
Operation)
11
Deck Drainage
Drainage System
•
Deck drains not provided where
necessary, or have inadequate size of
opening;
Deck drains and drainage systems
improperly constructed with inadequate
slopes or sharp directional changes;
Drainage system plugged or partially
plugged and not allowing for free and
unobstructed flow of water;
Drainage outlets discharging directly
onto structure components or roadways
below the deck;
Drainage outlets discharging directly
onto embankment without proper
provision for collecting, channelling and
controlling of discharge with splashpads,
spillways or gutters;
Inadequate provision for drainage at the
structure approaches.
•
Review deck drainage
requirements
Loss in riding comfort and potential loss
of vehicle control due to defects in the
component material;
Loss of protection to underlying surfaces
due to defects in the wearing surface
materials;
The inspector should look for the
following evidence of high water
levels, inadequate opening at the
structure and adverse affects on other
components of the structure:
Bending or buckling of the lower chord
of steel trusses in the downstream
direction by ice or heavy debris;
Ice scars and damage to substructures;
Coarse debris, such as branches and
small trees, caught or wedged under the
superstructure;
Fine debris, such as grass and twigs, on
fences, trees, embankments, structures,
etc.;
Wash lines on bare soil slopes;
Mud or silt deposited on embankments;
•
Resurface problem area
(Maintenance Operation)
•
Determine historical
frequency of flooding and
recorded water levels and
compare to current high
water elevation
Monitor water elevations
throughout year
Perform hydrology study
•
•
•
•
•
12
Slippery
Surfaces
Deck Top
•
•
13
Flooding/
Channel
Blockage
Streams &
Waterways
•
•
•
•
•
•
•
2-43
•
•
Oct. 2000
Suspected
Performance
Deficiency
Element Name
(Examples)
14
Undermining of
Foundation
15
Unstable
Embankments
Streams &
Waterways or
Foundation
Embankments
•
•
Marks and stains on structures.
Loss of material supporting foundations
due to scour or erosion.
Underwater Investigation
•
Settlement of embankment, slope
protections or approach roadway;
Sliding failure of the toe or slopes of the
embankment;
Surface or deep seated slips;
•
•
•
16
Loss of embankment material from
under foundations.
Other
2-44
Oct. 2000
SECTION 6 – MAINTENANCE NEEDS
Maintenance work is defined as any type of work that does not require the issuing of a capital construction
project. It includes routine maintenance items as well as targeted structural repairs to a specific element.
Routine Maintenance - preventative maintenance and minor repair work to an element that can be performed
without engineering direction. Routine maintenance is an important part of prolonging bridge life. It also
includes some urgent safety items that are not structural issues. It is usually carried out by bridge crews or road
maintenance personnel.
Structural Maintenance Work – is work to improve the structural capacity of a select element, and not part of
a larger construction project to improve the entire bridge. It generally requires engineering design drawings to
complete the work, but the work must be done in a timeframe that precludes a conventional capital construction
contract from being used. Structural Maintenance Work includes emergency repairs to restore structural
capacity as well as holding strategy repairs to select elements to maintain the structure in a safe condition until a
capital construction contract is carried out.
The bridge inspector should note the need for maintenance work when performing a detailed visual inspection,
and also the timeframe required. The following timeframes can be used:
-
-
-
“Urgent” applies to structure, motorist and pedestrian safety items that should be completed as soon as
possible. This includes routine maintenance items such as protruding expansion joint armouring,
missing electrical covers, pothole repairs and scaling loose concrete. It also includes emergency
structural maintenance items such as repairing fatigue cracks in girders, addition of temporary supports
to severely corroded beam ends and repairs to severely damaged piles.
“1 year” timeframe generally applies to serviceability items that should be done within about a 1 year
timeframe. This includes routine maintenance items such as bridge and deck drain cleaning, debris
removal from waterway and sidewalk surface repairs.
“2 year” timeframe applies to durability items that can be done in 2 or more years time. These items
must not be low enough in urgency that they will not become a serious concern before the next biennial
inspection, should they not be completed. At that time the urgency can be revised if it is approaching a
more critical state.
A maintenance list is then forwarded to maintenance crews for action – either to complete the routine
maintenance work or to initiate a structural maintenance contract for those items requiring more complex
procedures or engineering design. At the completion of the maintenance work, the maintenance crew should
inform the engineer responsible for the detailed inspection so that it can be confirmed that all safety related
maintenance was performed satisfactorily. A standard list of maintenance needs, and a description of each, is
shown in Table 6.1.
Table 6.1: Maintenance Needs
1
Maintenance Need
Lift and Swing Bridge
Maintenance
2
Bridge Cleaning
Description
The operation, maintenance and repair activities that are unique to lift and swing
bridge structures, including all mechanical equipment and electrical devices such
as signals, flashers, lighting, navigation lights, etc., but not including work defined
by other structural maintenance operations.
The cleaning of bridge components including:
1) Washing of bearings, bearing seats, truss members, etc.
2) Sweeping of bridge decks, curbs and gutters.
3) Removal of debris from expansion joints.
4) Debris pick-up or minor removal of aggregate.
5) Cleaning of catch-basins, man-holes and deck drains.
2-45(1)
Apr. 2008
7
Maintenance Need
Bridge Railing System
Maintenance
Painting Steel Bridge
Structures
Bridge Deck Joint Repair
Bridge Bearing
Maintenance
Repair to Structural Steel
8
Repair of Bridge Concrete
9
Repair of Bridge Timber
10
11
Bailey Bridges –
Installation, Maintenance
and Removal
Animal/Pest Control
12
13
Bridge Surface Repair
Erosion Control at Bridges
14
Concrete Sealing
15
Rout and Seal – Concrete
and Asphalt Pavement on
Bridge Decks
Bridge Deck Drainage
3
4
5
6
16
17
18
Scaling (Loose Concrete or
ACR Steel)
Other Maintenance
Description
The painting, repair and/or replacement of metal handrails, railing systems and
posts, as well as touch-up painting activities.
The preparation (sandblasting, etc.) and painting of structural steel. Includes
handrails when performed as part of an overall bridge painting operation.
The repair and/or replacement of expansion and/or fixed deck joints and end dams.
The adjustment, repair and/or replacement of bridge bearings. Includes all work
directly associated with bridge bearings.
The repair of all structural steel, including repair or replacement of steel
components, bolts and fasteners.
The repair of all concrete components of the structure, such as localized areas on
exposed decks or concrete end dams, curbs, pedestrian walks, concrete handrail
posts, parapet walls, abutments and piers, except when the repair is more directly
associated with one of the other defined bridge maintenance operations or the
quantity of repair is excessive for a maintenance operation.
The repair of all bridge timber, including the repair of timber decks on steel
bridges.
The installation, removal, repair and maintenance work that is unique to Bailey
Bridges, but not including work defined by other structural maintenance
operations.
The installation and maintenance of animal/pest control devices under bridge
structures such as pigeon-proofing.
The repair of bridge surfaces such as pothole patching.
Operations performed to prevent or repair damage due to erosion, such as scour at
abutments and around piers, and washouts on slopes. Includes removal of
obstructions to water flow, clearing of vegetation growth, etc.
The sealing or treatment of bridge concrete surfaces with approved materials, as
well as the preparation of surfaces prior to treatment.
The routing of joints and/or cracks in concrete and asphalt pavement and the filling
of same with joint fillers or rubberized asphaltic sealing compounds.
The repair, maintenance and replacement/ extension of deck drains. Includes
steaming and calcium application to unthaw.
The removal of loose delaminated concrete or delaminated patina of ACR steel
girders that pose a risk as a falling hazard.
A maintenance activity that does not fit into any other category.
2-45(2)
Apr. 2008
SECTION 7 - INSPECTION FORMS
The inspection forms required for recording field information are shown at the end of this Section. The form
usually consists of four main pages. A description of each page and the definitions of the various data entry
fields are contained below.
INVENTORY DATA AND HISTORICAL DATA (PAGE 1)
This is a one page summary of general inventory data and historical inspection/rehabilitation information. It is
often useful for the inspector to take this page to the field for reference purposes. The type of data on this page
is defined by the owner and usually originates from a main inventory database. The inspector should note any
discrepancies in the data when performing the inspection. An example of a typical form is shown at the end of
this section.
SCHEDULED IMPROVEMENTS AND APPRAISAL INDICES (PAGE 2)
In some jurisdictions, it is often of benefit to the inspector to know what improvements are planned for the
bridge. In addition, if some specific studies have been done (e.g. seismic, fatigue, etc.), a summary of the results
may be useful to the inspector in the field (e.g. The inspector may pay particular attention to certain details if
they have been identified as susceptible in a study). Examples of some of this optional appraisal data are shown
at the end of this section.
FIELD INSPECTION INFORMATION AND ADDITIONAL INVESTIGATIONS (PAGE 3)
FIELD INSPECTION INFORMATION
This page is completed in the field and consists of the following data fields:
Date of Inspection:
The date when the inspection was done.
Type of Inspection:
OSIM or Enhanced OSIM.
Inspector:
The name of the inspector and the name of the consulting engineering company (if applicable).
Others in Party: The other member(s) of the inspection team.
Access Equipment Used:
List of any special access equipment used in the inspection.
Weather:
Indicate the weather conditions at the time of the inspection.
Temperature: Indicate the temperature at the time of the inspection.
ADDITIONAL INVESTIGATIONS REQUIRED
These investigations are described in Part 3 of this manual. The required data and priority (urgency) of the
inspection is described below:
Priority – None:
Priority – Normal:
Priority – Urgent:
Investigation Notes:
Indicates that the investigation is not required.
Indicates that the investigation should be completed before the time of the next
inspection (usually within two years).
Indicates that the investigation should be completed as soon as possible.
Indicate any general comments about the investigations required.
OVERALL STRUCTURE NOTES
Recommended Work on Structure: This section is intended to include the inspector’s preliminary assessment of
the capital construction work that may be required. It is recognized that the
actual work required and timing will be determined as priority setting
methodologies are employed and the bridge progresses through preliminary
and detailed design. Recommended work is for work that requires a capital
2-46
Apr. 2008
construction contract. In general, enough work must be required on the
various elements to warrant placing the bridge on the rehabilitation
program. For example, defects such as spalled concrete on an abutment
wall, may not warrant that the bridge be placed on the rehabilitation
program just to repair the wall. Repairs classified as Maintenance,
including Structural Maintenance work, are recorded in the Maintenance
area for the specific element, as described in Section 6. Similarly,
functional deficiencies or additional investigations are also recorded in
other areas of the inspection form.
The inspector should record the magnitude of the recommended work and
the timeframe as described below.
Work Types on Structure
Minor Rehab: This includes work to elements of the bridge other than the deck. It can include
bearings, expansion joints, barrier walls or substructure elements.
Major Rehab: This must include major work to the deck to improve its overall condition. It includes
a patch-waterproof-pave rehab, deck overlay and deck replacement. It may also
include some other elements (i.e. bearings, barriers, etc.)
Structure Replacement: This involves complete replacement of the structure.
Timeframe
1 to 5 years:
A rehabilitation or replacement that can be done in a normal time frame. The
rehabilitation is to be designed and preferably completed in one to five years.
6 to 10 years: Some rehabilitation work is expected in 6 to 10 years.
Overall Comments:
Indicate any general comments or concerns related to the bridge, including any
concerns that do not necessarily apply to a particular element – also indicate any
recommended work comments.
Next Detailed Visual Inspection:
Indicate the date when the next biennial inspection is required. If deemed
necessary by the inspector, this could be at a time sooner than two years.
ELEMENT DATA (PAGE 4)
The data for each bridge element shall be shown on one table. The tables can be duplicated for as many
elements as exist for each bridge.
Element Group:
The main category of element (See Table 2.1)
Element Name: The individual element name and sub-element name (if applicable) (See Table 2.1)
Location:
A description of where the element is on the structure (e.g. East pier, portal bracing, etc)
Material:
The material the element is made of (See Table 7.1 )
Element Type:
The specific type of element (e.g. I-girder, elastomeric bearing, etc.)
Protection System:
The type of protection system for that element (e.g. Deck overlay type – latex,
cathodic protection; rebar type- coated, stainless, etc.)
Environment:
The degree to which the element is exposed to salt spray. (See Table 7.2 for examples).
Length, Width, Height: The dimensions used to calculate the total quantity of the element, as described in
Section 3, Table 3.1
Count:
The number of occurrences of the element under consideration (e.g. 6 girders)
Total Quantity:
The count times the quantity for one element (Units are defined in Table 2.1)
2-47
Apr. 2008
CONDITION DATA
This table is used to record the “severity and extent” of the material defects of the various bridge components as
described in Section 4. A close-up visual inspection is required for all elements. Appropriate special equipment
(Bridgemaster, bucket truck, ladders, etc) should be used to facilitate this assessment.
When recording the “extent” (quantity) that an element is in a particular condition state, the following guidelines
should be followed:
•
•
•
•
•
•
•
Select the appropriate inspection quantity units from Table 2.1 (m2, m., Each, All)
For Elements with units of m2 or m:
• The actual inspection quantity units should always be used for the part of the element in the Poor
Condition State (e.g. 15 m2). Percent should not be used unless the quantity in poor exceeds 50%.
Enter the estimated quantity in the 3 Condition States (Good, Fair, Poor). See the appropriate Condition
State Table in the Section 4.
Quantity in Excellent = Total - Quantities in other states
Elements with “each” as unit - give number of occurrences of the element in each State
Elements with “all” as unit - place entire quantity in one state
If an element is not completely visible, or the view is obstructed, quantities should be estimated and the
“Limited Inspection” box should be checked on the form.
SUSPECTED PERFORMANCE DEFICIENCIES
Suspected Performance Deficiencies, as described in Section 5, should be recorded if a potential deficiency
exists, or if a follow-up action is required. (e.g. strength evaluation, specialized inspection, etc.) Select
deficiencies from the pick list on page 3 of the form and enter the appropriate Code number.
MAINTENANCE NEEDS
Maintenance Needs should be selected from the pick list on page 3 of the form and the appropriate Code number
entered on the form, along with the timeframe. Written comments can also be made about maintenance needs.
For additional information, refer to Section 6,
COMMENTS
•
•
Comments should provide information on the poor condition state (e.g. How the quantity was estimated,
location of defects, etc.).
Comments can also be used to provide general information on the element.
RECOMMENDED WORK
This area should be used by the inspector to recommend work on an element and the time frame for completing
the work. It is used for recommending a specific action for the element, either rehabilitation or replacement. It
is not for maintenance work, functional deficiencies or additional investigations. Recommended work must
be consistent with the condition of the element, and as such, is usually driven by the quantity of defects in the
poor condition state. As a guide, the following ranges can be used to estimate the timing of recommended work
for the five major elements:
2-48
Apr. 2008
1 to 5 year
10% to 20% Poor
5% to 15% Poor
15% to 30% Poor
15% to 25% Poor
5% to 10% Poor
Deck Top
Deck Soffit
Barrier Wall
Expansion Joint
Girders
If the percent Poor is in the low end of the range, it is assumed that the timing would be closer to the 5 year
timeframe. Conversely, if the percent Poor is in the high end of the range, the timing would be closer to the 1
year timeframe. If the percent Poor for the element exceeds the upper bound of the range, the inspector should
ensure that safety of the structure is not a concern. For critical elements, the inspector may recommend the
element be rehabilitated even though the quantities in Poor condition are less than above. For elements not listed
above, the inspector may still record the recommended work and time frame if necessary.
The inspector is often unsure of the extent of the work required based solely on the visual inspection, thus, the
following general terms should be used:
Rehabilitation – Element requires patching, refacing, overlay, or partial replacement or,
Replacement – Element requires complete replacement.
Priority:
1 to 5 years:
A rehabilitation or replacement of element that is required in one to five years.
6 to 10 years: A rehabilitation or replacement of element that is required in 6 to 10 years.
Table 7.1: List of Materials
MATERIAL
Aluminum
Asphalt
Cast Iron
Cast-in-place concrete
Corrugated steel
Gravel
Hybrid
Masonry
Mass concrete
Plastic
Precast concrete
Retained soil system
Steel
Weathering steel
Wood
Other
Table 7.2: Examples of Environmental Exposure
Severe
Exposed Concrete Deck
Moderate
Concrete Deck with
waterproofing
Exterior Soffit
Outside face of barrier wall
Railings and inside face of
Barrier Walls
Abutment in splash zone
Abutment at expansion joint
Pier in splash zone
Pier at expansion joint
End Portion of Beams (at
joints)
Benign
Interior Soffit
Abutment with no joint
(integral abutment)
Pier with no joint (where
deck continuous)
Remainder of Beams
Joints
2-49
Apr. 2008
Ontario Structure Inspection Manual – Inspection Form
MTO Site Number:
Inventory Data:
Structure Name
Main Hwy/Road #
On
Under
Crossing
Type:
Navig. Water
Road
Non-Navig. Water
Ped.
Other
Rail
Hwy/Road Name
Structure Location
Latitude
Longitude
Owner(s)
Heritage
Designation:
MTO Region
Road Class:
MTO District
Posted Speed
Old County
AADT
Geographic Twp.
Inspection Route Sequence
Structure Type
Interchange Number
Not Cons.
Cons./not App.
List/not Desig.
Desig./not List
Desig. & List
Freeway
Collector
Local
No. of Lanes
% Trucks
Total Deck Length
(m)
Interchange Structure Number
Overall Str. Width
(m)
Min. Vertical Clearance
Total Deck Area
(sq.m)
Special Routes:
Roadway Width
(m)
Detour Length Around Bridge
Skew Angle
(Degrees)
Direction of Structure
No. of Spans
Arterial
(m)
Transit
Truck
School
Bicycle
(km)
Fill on Structure
(m)
Span Lengths
(m)
Historical Data:
Year Built
Year of Last Major Rehab.
Last OSIM Inspection
Last Evaluation
Last Enhanced OSIM Inspection
Current Load Limit
Enhanced Access Equipment
(ladder, boat, lift, etc.)
Load Limit By-Law #
Last Underwater Inspection
By-Law Expiry Date
/
/
Last Condition Survey
Rehab History: (Date/description)
Page 1
2-50
Apr. 2008
Nov. 2003 Revision
(tonnes)
MTO Site Number:
Scheduled Improvements:
Regional Priority
Number
Programmed Work
Year
Nature of Program Work:
Appraisal Indices:
Comments
Fatigue
Seismic
Scour
Flood
Geometrics
Barrier
Curb
Load Capacity
Page 2
2-51
Oct. 2000
MTO Site Number:
Field Inspection Information:
Date of Inspection:
Type of Inspection:
OSIM
Enhanced OSIM
Inspector:
Others in Party:
Access Equipment
Used:
Weather:
Temperature:
Priority
Normal
Additional Investigations Required:
None
Urgent
Material Condition Survey
Detailed Deck Condition Survey:
Non-destructive Delamination Survey of Asphalt-Covered Deck:
Concrete Substructure Condition Survey:
Detailed Coating Condition Survey:
Detailed Timber Investigation
Post-Tensioned Strand Investigation
Underwater Investigation:
Fatigue Investigation:
Seismic Investigation:
Structure Evaluation:
Monitoring
Monitoring of Deformations, Settlements and Movements:
Monitoring Crack Widths:
Investigation Notes:
Overall Structure Notes:
Recommended Work on
Structure:
Timing of Recommended Work:
None
Minor Rehab.
1 to 5 years
Major Rehab.
Replace
6 to 10 years
Overall Comments:
Date of Next Inspection:
Suspected Performance Deficiencies
01
02
03
04
05
Load carrying capacity
Excessive deformations (deflections & rotations)
Continuing settlement
Continuing movements
Seized bearings
Maintenance Needs
Lift and Swing Bridge Maintenance
01
Bridge Cleaning
02
Bridge Handrail Maintenance
03
Painting Steel Bridge Structures
04
Bridge Deck Joint Repair
05
Bridge Bearing Maintenance
06
Page 3
06
07
08
09
10
11
Bearing not uniformly loaded/unstable
Jammed expansion joint
Pedestrian/vehicular hazard
Rough riding surface
Surface ponding
Deck drainage
07
08
09
10
11
12
Repair to Structural Steel
Repair of Bridge Concrete
Repair of Bridge Timber
Bailey bridges - Maintenance
Animal/Pest Control
Bridge Surface Repair
2-52
12
13
14
15
16
13
14
15
16
17
18
Slippery surfaces
Flooding/channel blockage
Undermining of foundation
Unstable embankments
Other
Erosion Control at Bridges
Concrete Sealing
Rout and Seal
Bridge Deck Drainage
Scaling (Loose Concrete or ACR Steel)
Other
Oct. 2000
Apr. 2008
Element Data
Element Group:
Element Name:
Location:
Material:
Element Type:
Environment:
Protection System:
Benign / Moderate / Severe
Condition
Units
2
Data:
m / m / each / % / all
Comments:
Recommended Work:
Element Group:
Element Name:
Location:
Material:
Element Type:
Environment:
Protection System:
Rehab
1-5 years
Recommended Work:
Element Group:
Element Name:
Location:
Material:
Element Type:
Environment:
Protection System:
Exc.
Rehab
1-5 years
Recommended Work:
Rehab
1-5 years
Fair
Poor*
Perform.
Deficiencies
Maintenance Needs:
Urgent
1 year
2 year
Length:
Width:
Height:
Count:
Total Quantity:
Limited Inspection
Exc.
Good
Fair
Poor*
Perform.
Deficiencies
Maintenance Needs:
Replace
6-10 years
Condition
Units
2
Data:
m / m / each / % / all
Comments:
Good
Replace
6-10 years
Condition
Units
Data:
m2 / m / each / % / all
Comments:
Length:
Width:
Height:
Count:
Total Quantity:
Limited Inspection
Urgent
1 year
2 year
Length:
Width:
Height:
Count:
Total Quantity:
Limited Inspection
Exc.
Good
Fair
Poor*
Perform.
Deficiencies
Maintenance Needs:
Replace
6-10 years
Urgent
1 year
2 year
* A quantity must be estimated using the appropriate unit (e.g. m2). Percent should not be used.
2-53
(a)
Apr.
2008
Oct.
2000
SECTION 8 – EXAMPLES
The following pages depict examples of various material defects and performance deficiencies. The
photographs are listed in order of Element Group first and then by Element. For each photograph, the
Condition State is identified for the portion on the element with the worst material defects. During an actual
inspection, the quantity of the element in each condition state would be recorded.
Contents
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12
8.13
8.14
Page
Abutments......................................................................................................................2-54
Approaches ....................................................................................................................2-63
Barriers...........................................................................................................................2-66
Beams/Main Longitudinal Elements..............................................................................2-70
Bracing...........................................................................................................................2-72
Coatings .........................................................................................................................2-74
Culverts..........................................................................................................................2-77
Decks .............................................................................................................................2-79
Embankments & Streams...............................................................................................2-86
Foundations....................................................................................................................2-93
Joints ..............................................................................................................................2-95
Piers ...............................................................................................................................2-99
Retaining Walls............................................................................................................2-102
Trusses/Arches.............................................................................................................2-103
2-53
Oct. 2000
8.1 - ABUTMENTS
Figure 8.1(a)
Concrete Abutment Wall
Condition State: Fair/Poor
•
Numerous medium cracks and several wide cracks with penetration of water through
wall and efflorescence.
Performance Deficiency: Load Carrying Capacity
•
Deterioration present may reduce the strength of the wall.
required to determine the extent of strength reduction.
Figure 8.1(b)
An evaluation is
Wood Lagging - Abutment Wall
•
Light weathering of wood.
Performance Deficiency: None
•
Slight movement of piles and lagging which has stabilized. No significant effect on
other components.
Oct. 2000
2-54
Figure 8.1(c)
Wood Crib - Abutment Wall
•
Very severe decay, crushing and splintering of wood.
Performance Deficiency: Continuing Movement; Continuing Settlement
•
Continuing increasing movement and a loss of strength affecting the stability of
the structure.
Figure 8.1(d)
Masonry Abutment Wall
•
Medium loss of Mortar.
•
Wall is satisfactorily supporting superstructure loads.
2-55
Oct. 2000
Figure 8.1(e)
•
Medium cracking under the bearing seat.
•
No loss of bearing area.
Figure 8.1(f)
•
Very severe disintegration of concrete.
Performance Deficiency: Bearing Not Uniformly Loaded/Unstable
•
Bearing seat area reduced.
2-56
Oct. 2000
Figure 8.1(g)
Concrete Ballast Walls
•
Light surface scaling.
•
No performance defects.
Figure 8.1(h)
Concrete Ballast Wall
Condition Statement: Poor
•
Very severe delamination, spalling and corrosion of exposed reinforcement.
Performance Deficiency: Continuing Movement / Load Carrying Capacity
•
Continuing movement. Loss of section may affect the capacity of wall to retain
backfill. An evaluation is required to determine the extent of strength reduction.
2-57
Oct. 2000
Figure 8.1(i)
Steel Plate Sliding Bearing
•
Light rusting.
•
Anchor bolts near end of travel in slots of base plate.
further expansion of superstructure.
Minor allowance for
Maintenance Needs: Bridge Bearing Maintenance
•
Cleaning of debris around bearing required.
Figure 8.1(j)
TFE Elastomeric Bearing
Condition State: Fair/Poor
•
Anchor bolts severely bent. Elastomer being squeezed out.
Performance Deficiency: Continuing Movement
•
Movement of structure not adequately restrained.
2-58
Oct. 2000
Figure 8.1(k)
Laminated Elastomeric Bearing
•
Medium bulging and cracks in elastomeric pad.
Figure 8.1(l)
Pot Bearing
•
TFE squeezed out.
Performance Deficiency: Seized Bearings
•
Almost complete loss of sliding capability.
2-59
Oct. 2000
Figure 8.1(m)
•
Light corrosion.
•
Rocker should be tilting toward the ballast wall based upon temperature of 20o C at
the time of inspection. Rocker in danger of falling over during colder weather.
Figure 8.1(n)
•
No material defects.
•
Bearing in danger of collapse.
2-60
Oct. 2000
Figure 8.1(o)
Roller Bearing
•
Very severe corrosion.
Performance Deficiency: Seized Bearings
•
Rollers frozen.
No capability for movement.
Figure 8.1(p)
Concrete Wingwall
•
Narrow cracking with efflorescence.
•
No evidence of movement.
Wall is satisfactorily retaining backfill.
2-61
Oct. 2000
Figure 8.1(q)
Concrete Wingwall
•
Very severe erosion, spalling and delaminations.
Performance Deficiency: Continuing Movement / Load Carrying Capacity
•
Very severe section loss and continuing movement critically affecting the strength
and stability of the wall. An evaluation is required to determine the extent of
strength reduction.
2-62
Oct. 2000
8.2 - APPROACHES
Figure 8.2(a)
Concrete Approach Slab
•
No visible defects.
Performance Deficiency: Pedestrian/Vehicular Hazard / Rough Riding Surface
•
Approach has settled by 20 mm adjacent to the bridge, and provides a rough
transition onto the bridge.
Figure 8.2(b)
Concrete Sidewalk
•
Very severe spalling.
Performance Deficiency: Pedestrian/Vehicular Hazard
•
Curb inadequate to prevent vehicles from climbing curb.
2-63
Oct. 2000
Figure 8.2(c)
Wood Curb
•
Insignificant collision damage and deterioration of wood.
•
Satisfactory curb height, with no displacements or projections.
Figure 8.2(d)
Concrete Sidewalk
•
Severe scaling and spalling with exposure of severely corroded reinforcement.
Performance Deficiency: Pedestrian/Vehicular Hazard
•
Sidewalk surface irregular with large spalls and very severe scaling presenting
difficulty for pedestrian passage.
2-64
Oct. 2000
Figure 8.2(e)
Wood Sidewalk
•
Light weathering of wood planks.
Performance Deficiency: Slippery Surfaces
•
Slightly slippery surface when wet.
Figure 8.2(f)
Gravel Approach
Condition State: Not Applicable
Performance Deficiency: Rough Riding Surface
•
Approaches are slightly rough and should be re-graded.
Maintenance Needs: Bridge Surface Repair
Gravel should be removed from the deck surface.
2-65
Oct. 2000
8.3 - BARRIERS
Figure 8.3(a)
Parapet Wall
Parapet Wall
•
Light defects.
•
Hand Railing
•
Permanent deformation of hand railing.
•
An evaluation is required to determine the extent of
strength reduction.
Figure 8.3(b)
Barrier Wall
•
Light scaling.
•
2-66
Oct. 2000
Figure 8.3(c)
Concrete Railing
•
Many broken rails and posts.
•
An evaluation is required to determine the extent of strength reduction.
Figure 8.3(d)
Concrete Railing
•
•
2-67
Oct. 2000
Figure 8.3(e)
Steel Railing with Steel Posts (concrete filled)
Condition State (for posts): Poor
•
Cracks in posts.
•
Figure 8.3(f)
Steel Railing with Concrete Posts
•
Many broken areas.
•
2-68
Oct. 2000
Figure 8.3(g)
Concrete Guide Rail
•
•
Figure 8.3(h)
Steel Flex Beams
•
Permanent deformation of flex beam.
•
2-69
Oct. 2000
8.4 - BEAMS/Main Longitudinal Elements
Figure 8.4(a)
Floor Beam of Steel Through Truss
•
Very severe corrosion with perforation of floor beam web.
Performance Deficiency:
•
More than 20% loss of cross-section of floor beam. An evaluation is required to
determine the extent of strength reduction.
Figure 8.4(b)
Reinforced Concrete Girders
•
A few wide longitudinal cracks due to corrosion of reinforcement.
•
Cracking has little effect on girder capacity.
2-70
Oct. 2000
Figure 8.4(c)
Concrete T-Beam
•
Full height, medium shear crack.
•
Potentially inadequate beam capacity. An evaluation is required to determine the
extent of strength reduction.
Figure 8.4(d)
Steel Beam
•
Very severe corrosion of web and bottom flange.
•
Possible loss of load carrying capacity. An evaluation is required to determine the
2-71
Oct. 2000
8.5 - BRACING
Figure 8.5(a)
Sway Bracing and Bottom Lateral Bracing
•
Light corrosion of both bracing systems.
•
Bracings are providing satisfactory lateral support.
Figure 8.5(b)
Bottom Lateral Bracing
•
Light corrosion over the surfaces of bracing angles.
•
Bracing is providing satisfactory lateral support.
2-72
Oct. 2000
Figure 8.5(c)
Top Lateral Bracing in Steel Through Truss
•
Permanent deformation of member.
•
Possible loss of strength and ability to provide lateral support, due to
deformation. An evaluation is required to determine the extent of strength
reduction.
2-73
Oct. 2000
8.6 - COATINGS
Figure 8.6(a)
Through Truss - Connection of Primary Components
•
No defects in coating material.
Performance Deficiency: Not Applicable
Figure 8.6(b)
Railing
•
Material defects and severe surface rust (Rust Condition Rating – Category 4).
2-74
Oct. 2000
Figure 8.6(c)
Connection of Primary Components
•
Coating is peeling.
Figure 8.6(d)
Through Truss - Connection of Primary Components
•
Coating is peeling.
2-75
Oct. 2000
Figure 8.6(e)
Steel Pony Truss
•
Material defects and medium surface rust (Rust Condition Rating - Category 3).
Figure 8.6(f)
Truss Primary Connection at Abutment Bearing
•
Material defects and severe surface rust (Rust Condition Rating - Category 4) of
the connection surface.
2-76
Oct. 2000
SECTION 8.7 - CULVERTS
Figure 8.7(a)
Multi-plate Pipe Arch
•
Medium crimping of corrugations.
zone only.
Quantity is measured as the area of the crimpling
•
Possible inadequate capacity to support applied loading.
Figure 8.7(b)
•
Severe cracks along bolt line in the valley corrugations of the haunch lap joint.
Quantity is measured as the area of the circumferential band where cracks exist
(i.e. there is a small band (under the ridge bolt) that is not cracked and is not
Poor.
Performance Deficiency: Excessive Deformations
Severe local deformation has occurred. Present strength is just adequate, but local
or general collapse of the pipe may occur suddenly.
2-77
(a)
Apr.
Oct. 2008
2000
Figure 8.7(b1)
•
Deformation and reverse curvature of culvert roof, plus cusping(separation of
plates at joint <10mm. Quantity is measured as the area of the circumferential
band for the length that reverse curvature extends.
Performance Deficiency: Excessive Deformations, Load Carrying Capacity
•
Possible inadequate capacity to support applied loading and local or general
collapse may occur suddenly.
Figure 8.7(b2)
•
Separation of culvert units.
separation occurs.
Performance Deficiency:
•
Quantity is measured as the band area where the
Load Carrying Capacity
Present strength appears adequate, but local continued loss of support material for
soil-steel culvert may lead to general collapse of the pipe.
2-77
(b)
Apr. 2008
Figure 8.7(b3)
Condition State: Good/Fair
•
Moderate rust along waterline, light rust elsewhere.
Figure 8.7(b4)
•
Severe rusting along floor of culvert. Quantity is measured as the circumferential
band area where there are perforations and the actual area of corrosion where the
section loss is >10%, but no perforations exist.
•
Severe rusting has occurred. Present strength is just adequate, but local or
general collapse of the pipe may occur suddenly.
2-77
(c)
Apr. 2008
Figure 8.7(c)
Wood Culvert
•
Walls breaking up and soil entering into the waterway. Washout of fill behind the
walls.
•
Severe sway and continuing movement of the walls with possible sudden collapse.
Figure 8.7(d)
Concrete Open Footing Culvert
•
Light deterioration of concrete.
•
Culvert supporting fill satisfactorily.
Maintenance Needs: Erosion Control at Bridges
•
Heavy vegetation growth should be cleared.
2-78
Oct. 2000
8.8 - DECKS
Figure 8.8(a)
Exposed Concrete Deck of a Voided Slab
•
Medium longitudinal cracks in deck top surface at the void locations.
•
Material defects unlikely to cause reduction in load carrying capacity.
Figure 8.8(b)
Exposed Concrete Deck
•
Medium transverse cracks in deck top surface.
•
Cracking has no significant effect on the load capacity or load distribution of the
deck.
2-79
Oct. 2000
Figure 8.8(c)
Concrete Deck
•
Many locations of medium scaling and surface staining due to corrosion of
reinforcement.
•
Deck is satisfactorily carrying load but provides a slightly rough ride around the
deck joint.
Figure 8.8(d)
Concrete Deck
•
Previously repaired delaminated areas are delaminating again.
•
Deck provides a slightly rough ride.
2-80
Oct. 2000
Figure 8.8(e)
Deck Drain (Hole in Deck)
•
Medium deterioration, with a full depth wide crack, honeycombing and scaling of
concrete at the drain location.
Performance Deficiency: Deck Drainage
•
A proper drain has not been installed.
structure components below.
Figure 8.8(f)
Discharge runs along soffit and onto
Steel Deck Drain
•
Medium corrosion over 25% of drainage system.
•
Drain flows freely and discharges well away from other components.
2-81
Oct. 2000
Figure 8.8(g)
Deck Drain With Basin
•
Light corrosion of basin.
Performance Deficiency: Surface Ponding
Slight accumulation of debris in the basin, and evidence of slight ponding of water
around the basin.
Maintenance Needs: Bridge Cleaning
•
Debris should be removed from catch basin.
Figure 8.8(h)
Drainage System
•
Insignificant and localized deterioration of drainage trough under deck joint.
•
Slight accumulation of debris in the trough, not affecting the adequacy of the
system.
2-82
Oct. 2000
Figure 8.8(i) Drainage System
•
Light corrosion of corrugated pipe deck drain. Drainage system on abutment in good
condition.
Maintenance Needs:
•
Pipe drain discharges directly onto embankment causing severe erosion.
Figure 8.8(j)
Drainage System
•
Drain pipe broken off at connection.
Performance Deficiency: Deck Drainage
Maintenance Needs: Bridge Deck Drainage / Erosion Control at Bridges
•
Drain discharging directly onto embankment causing very severe erosion.
2-83
Oct. 2000
Figure 8.8(k)
Rigid Frame, Thick Slab Soffit
•
Medium longitudinal cracks with water leakage and deposits on soffit.
•
No loss of load carrying capacity.
Figure 8.8(l)
Thick Slab Soffit
•
Very severe pattern cracking with severe spalling and exposed corroded
reinforcement.
•
Material defects may result in marginal loss of load carrying capacity. An
evaluation is required to determine the extent of strength reduction.
2-84
Oct. 2000
Figure 8.8(m)
Soffit of a Thin Slab
Condition State: Fair to Poor
•
Medium to wide cracks with local delamination and spalling of concrete over the top
flanges of the floor beams and stringers.
•
Material defects which may affect deck performance locally. An evaluation is
required to determine the extent of strength reduction.
Figure 8.8(n)
Asphalt Wearing Surface on Laminated Wood Deck
•
Very severe breaking up of the wearing surface with very severe deterioration of
the deck laminates in many places.
Performance Deficiency: Load Carrying Capacity / Pedestrian/Vehicular Hazard
•
Some areas of deck may not support truck wheel loads. An evaluation is required to
determine the extent of strength reduction.
•
Wearing surface is irregular, resulting in moderate difficulty in maintaining
vehicle control.
2-85
Oct. 2000
8.9 - EMBANKMENTS & STREAMS
Figure 8.9(a)
Embankments
•
Many very deep, closely spaced gullies. Loss of embankment material to top of
footing.
•
Minor movement has stopped. Embankment is essentially stable.
Figure 8.9(b)
Embankments
•
Loss of 30% to 40% of material due to scour at the toe of slope.
Performance Deficiency: Unstable Embankments
•
Embankment is unstable. Progressive failure of slope will continue.
2-86
Oct. 2000
Figure 8.9(c)
Embankments
Right Embankment
•
Scour of 30% to 40% of embankment.
Performance Deficiency: Unstable Embankment
•
Embankment is unstable. Progressive failure will continue.
Left Embankment
•
Scour of over 40% of embankment.
•
Embankment has collapsed. Stability of approach is critically affected.
2-87
Oct. 2000
Figure 8.9(d)
Random Rip-Rap Slope Protection
•
No evidence of material deterioration.
Figure 8.9(e)
Grass Slope Protection
•
Loss of grass to over 20% of embankment.
•
Loss of protection to 20% of the embankment.
2-88
Oct. 2000
Figure 8.9(f)
Cast-In-Place Concrete Slope Protection
•
No material deterioration of concrete slabs.
Performance Deficiency: Continuing Settlement; Continuing Movement
•
A few areas of minor movement and settlement.
Figure 8.9(g)
Precast Concrete Slope Protection
•
Less than 20% of the slabs broken.
Performance Deficiency: Continuing Settlement; Continuing Movements
•
Severe settlement and movement of the slope protection.
2-89
Oct. 2000
Figure 8.9(h)
Streams
•
Degradation of stream bed to bottom of footing.
Performance Deficiency: Flooding/Channel Blockage
•
Maximum high water marks above soffit of beams.
Figure 8.9(i)
Streams
•
Aggradation of right bank and erosion of left bank resulting in severe change in
stream alignment and flow at the structure.
Performance Deficiency: Undermining of Foundation
•
Stream encroaching against wingwall and substructure with severe erosion of
embankment and scour under the foundation.
2-90
Oct. 2000
Figure 8.9(j)
Streams
•
Medium aggradation and siltation of stream bed with moderate growth of vegetation.
•
Channel blockage reducing opening at structure.
Figure 8.9(k)
Streams
•
Aggradation of stream bed having a severe effect on stream flow at the structure.
•
Partial blockage of the opening at the structure.
2-91
Oct. 2000
Figure 8.9(l)
Streams
•
Very severe deposition of debris after a flood.
•
Debris carried and deposited against structure after a flood causing substantial
damage to piles and blocking stream flow.
Figure 8.9(m)
Streams
•
Medium local aggradation of the streambed.
•
Flooding of stream over deck occurring every year. Very severe damage to structure
by debris carried during flood.
2-92
Oct. 2000
8.10 - FOUNDATIONS
Figure 8.10(a)
Foundation
•
Localized area with spalling and disintegration. This deterioration should be
included with the “Abutment Wall” element.
•
No visible movement of footing, abutment or superstructure. Loss of section not
affecting foundation capacity.
Figure 8.10(b)
Foundation
•
Previous settlement of wingwall has stabilized.
2-93
Oct. 2000
Figure 8.10(c)
Foundation
•
Movement of foundation has stabilized. It has produced wide cracks in abutment but
has not affected the stability of the abutment.
Figure 8.10(d)
Foundation
Performance Deficiency: Continuing Movements
•
Continuing increasing movement of foundation has affected stability of the pier and
the superstructure.
2-94
Oct. 2000
8.11 - JOINTS
Figure 8.11(a)
Finger Plate Expansion Joint
•
Light rust.
Performance Deficiency: Jammed Expansion Joint / Pedestrian/Vehicular Hazard
•
No room for further expansion, joint alignment poses danger to traffic.
Figure 8.11(b)
Compression Seal Joint
•
Seal is leaking.
2-95
Oct. 2000
Figure 8.11(c)
Paved-Over Joint
•
Significant cracking of asphalt pavement.
Joint is leaking.
•
Rough ride across the joint.
Figure 8.11(d)
Ethylene Vinyl Acetate Seal
•
Seal is leaking.
2-96
Oct. 2000
Figure 8.11(e)
Multiple Seal Joint
•
Seal torn and joint is leaking.
Figure 8.11(f)
Rubber Cushion Joint
•
Joint is leaking.
2-97
Oct. 2000
Figure 8.11(g)
Horizontally Bolted Seal
•
Light abrasion of the seal due to debris.
Performance Deficiency: Jammed Expansion Joint
•
Deck movement severely restricted by debris.
Maintenance Needs: Bridge Cleaning
•
Debris should be cleared as part of general maintenance.
2-98
Oct. 2000
8.12 - PIERS
Figure 8.12(a)
Concrete Pier Cap
•
Very severe spalling and corrosion of exposed reinforcement.
•
An evaluation is required to determine the extent of load carrying capacity.
Figure 8.12(b)
Concrete Pier Column
•
Very severe delamination and spalling of the column, with exposed reinforcement.
•
Section loss will have minimal effect on load carrying capacity.
2-99
Oct. 2000
Figure 8.12(c)
Steel Pier Bent Base
•
Medium corrosion; 5% to 10% loss of section locally.
•
Component capacity marginally affected by loss of section.
Figure 8.12(d)
Wood Trestle
•
Light decay in piles.
•
No evidence of movement. Piles satisfactorily supporting load without distress.
2-100
Oct. 2000
Figure 8.12(e)
•
Masonry Pier
Medium crack in stone.
•
Previous movement has stabilized.
Figure 8.12(f)
Disc Bearing
•
Light rusting and stainless steel sliding plate is separating slightly.
•
Movement capacity affected less than 10%.
2-101
Oct. 2000
8.13 - RETAINING WALLS
Figure 8.13(a)
Precast Concrete Retaining Wall
•
Medium Cracking of Precast Units.
•
No evidence of movement. Wall satisfactorily retaining fill.
Figure 8.13(b)
Bag Mortar Retaining Wall
•
Minor loss of material at the joints.
•
A few locations of local minor movement. Wall satisfactorily retaining fill.
Vegetation growth should be removed as part of general maintenance.
Oct. 2000
2-102
8.14
Figure 8.14(a)
TRUSSES/ARCHES
Steel Through Truss Connection
•
Severe corrosion over a plan area greater than 10%. Severe connection deficiency
exists.
Possible loss of load carrying capacity. An evaluation is required to determine the
Figure 8.14(b)
Sway Frame Connection.
•
Medium corrosion over more than 40% of the connection. No connection deficiency
since no areas of severe corrosion exist on gusset.
•
Minimal loss of strength due to corrosion.
2-103
Oct. 2000
•
Figure 8.14(c)
Vertical Member of Steel Through Truss
•
15% to 20% of cross section removed to install guide rail.
•
Possible loss of load carrying capacity due to loss of section, and subsequent
buckling. An evaluation is required to determine the extent of strength reduction.
Figure 8.14(d)
Concrete Bowstring Arch
•
Very severe scaling of arch rib.
•
Marginal loss of performance. Material defects unlikely to cause reduction in load
carrying capacity.
2-104
Oct. 2000
Figure 8.14(e)
Concrete Spandrel Arch
•
Very wide crack in the arch rib.
•
Crack extends about 100 mm into the rib. Material defects unlikely to cause
reduction in load carrying capacity.
2-105
Oct. 2000
APPENDIX A – COMBINED MATERIAL DEFECTS AND CONDITION STATE
TABLES
This appendix contains a simplified table for material defects and condition states by combining the information from
OSIM Part 1, Section 2 and Part 2, Section 4.
Table
Page
A.1
Concrete ................................................................................................................ 2-107
A.2
Steel/Aluminum ..................................................................................................... 2-109
A.3
Wood ..................................................................................................................... 2-110
A.4
Masonry ................................................................................................................. 2-111
A.5
Asphalt Wearing Surface ....................................................................................... 2-112
A.6
Asphalt Covered Concrete Deck ........................................................................... 2-113
A.7
Coating .................................................................................................................. 2-114
2-106
Apr. 2008
Table A.1
Concrete (Reference: Part 1, Section 2.2 and Part 2, Table 4.5)
CONDITION STATE
DEFECT
GOOD (LIGHT)
FAIR (MEDIUM)
POOR
(SEVERE / VERY SEVERE)
Local flaking/loss of surface portion of concrete or mortar due to freeze-thaw
Scaling
Up to 5 mm depth
6 - 10 mm depth
> 10 mm depth
Physical deterioration or breaking down of the concrete into small fragments
Disintegration
Erosion
All
Deterioration of concrete brought about by water-borne sand and gravel particles scrubbing against
surfaces
All
Deterioration of reinforcement by electrolysis
Corrosion of
Reinforcement
Delamination
Due to drains/chairs
Rust stains from reinforcement
Exposed reinforcement with
rust
Discontinuity of the surface concrete which is substantially, but not completely detached from
concrete below or above it.
All
Fragments which have been detached from a larger concrete mass
Spalling
All
Linear fracture which extends partly or completely through the member.
Cracking
< 0.3 mm
0.3 - 1.0 mm wide
> 1.0 mm wide
Aggregates react adversely with the alkalies in cement to produce a highly expansive alkali-silica gel
AlkaliAggregate
Reaction
Hairline pattern cracks
< 0.1 mm
Narrow pattern cracks 0.1 - 0.3
mm wide
2-107
Medium-wide pattern cracks
> 0.3 mm wide
Apr. 2008
Table A.1
Concrete (Reference: Part 1, Section 2.2 and Part 2, Table 4.5) continued
CONDITION STATE
DEFECT
GOOD (LIGHT)
Honeycombing
FAIR (MEDIUM)
Produced due to the improper or incomplete vibration of the concrete which results in voids
being left in the concrete where the mortar failed to completely fill the spaces between the
coarse aggregate particles
Holes up to 25 mm diameter Holes 25 - 50 mm diameter
Pop-Outs
POOR
Holes more than 50 mm
diameter
Shallow conical depressions resulting from the breaking away of small portions of the concrete
surface, due to the expansion of some aggregates due to frost action.
Holes up to 25 mm diameter Holes 25 - 50 mm diameter
Holes more than 50 mm
diameter
Separation of concrete into layers prior to hardening, due to over- vibration.
Stratification
ALL
Concrete not uniform due to falling concrete (poor placement)
Segregation
ALL
Caused by hardened concrete prior to the next adjacent pour
Cold Joints
ALL
leaching chemicals and depositing them on the surface - efflorescence
Deposits
ALL
Wearing caused by vehicles or snow-plough blades
Abrasion
ALL
Wear
Result of dynamic and/or frictional forces generated by vehicular traffic, coupled with the
abrasive influx of sand, dirt and debris
ALL
Slippery Concrete
Surface
Smooth surface resulting from the polishing of the concrete deck surface by the action of
repetitive vehicular traffic
ALL* include suspected
performances deficiency of
“slippery surface”
Concrete soffit surface is wet or damp
Active Wet Areas
Wet but no cracks
2-108
Wet with cracks
Apr. 2008
Table A.2
STEEL/ALUMINUM (Reference: Part 1, Sect. 2.3 and 2.6, Part 2 Table 4.15,4.16, and 4.17)
CONDITION STATE
DEFECT
GOOD (LIGHT)
FAIR (MEDIUM)
POOR
(SEVERE / VERY
SEVERE)
Deterioration of steel by chemical/electro-chemical reaction resulting from exposure to air, moisture, deicing salts, industrial fumes and other chemicals/contaminants in the environment in which it is placed
Corrosion
No section loss, loose
rust/pitting in paint -
< 10% section loss, small scales
or flakes -
Early signs of patina damage
Flaking of patina
> 10% section loss, extensive
rust/perforations *
Steel members can take the form of bending, buckling, twisting or elongation.
Corrugate Steel Pipe (CSP) culverts can exhibit cusping (abrupt change in curvature, typically at
seam), crimping (local buckling of culvert wall), global deformation (change in original curved
shape), and bolt tilting (bearing failure of bolts).
For members: ALL (Estimate
repair area) *
Permanent
Deformations
Cusping or crimping of culverts
<10mm in height.
Cusping or crimping of
culverts >10mm in height *
Global Deformation <10% of
culvert diameter
Global Deformation >10% of
culvert diameter and reverse
curvature *
Bolt Tilting
Cracking
Are linear fracture in the steel extending partially or completely through the member. They are mainly
caused by fatigue, which can lead to brittle fracture (member cracks completely) through without prior
warning)
Cracks perpendicular to stress are very serious and
should have immediate action taken.
ALL *
(Estimate repair area)
Loose connections can occur in bolted, riveted or clamped connections. They may be caused by
corrosion of the connector, gusset plates or fasteners, excessive vibration, overstressing, cracking, or
the lack of proper tightening during construction.
Connection
Deficiencies
Based on the condition of the worst component within the connection
Depends on percentage of Loose Bolts or Plan Area with severe corrosion
< 5% loose bolts or severe rust < 10% loose bolts or severe rust
or cracks
> 10% loose bolts or severe
rust or cracks
* - For CSP culverts, all portions in the Poor Condition State except corrosion without perforations (i.e. cusping,
crimping, deformations, cracks and corrosion with perforations) the area shall be taken to include the entire
circumference
2-109
Apr. 2008
Table A.3
WOOD (Reference: Part 1, Sect. 2.4 and Part 2 Table 4.19)
DEFECT
GOOD (LIGHT)
Weathering
Checks
Splits
Shakes
Weathering
Checks, Splits,
Shakes
Rot or Decay
Insect Damage
Abrasion and
Wear
Cracking,
Splintering,
Crushing and
Shattering
CONDITION STATE
FAIR (MEDIUM)
POOR
Gradual deterioration of wood due to exposure to the actions of sun, rain, wind, frost and
atmospheric pollutants
Longitudinal tissue separations on the side grain of wood members
Severe tissue separations extending from the side into the end
Tissue separations which follow the circular annual growth rings, and are visible on the end
grain
< 5% into member
5—10% into member
> 10% into member
< 5% into member
5—10% into member
> 10% into member
Biological decomposition of wood caused by micro-organisms called fungi
Slight change in colour Surface is discoloured and slight Surface is fibrous or crumbly
but wood solid (< 5%
hollow sound (5% - 10% loss)
and hollow sounding or
loss)
surface and interior is crumbly
and wood is weak (> 10 % loss)
Consequence of the tunnelling/boring by larvae/mature insects through the wood resulting in loss
of section
Holes are present (< 5% Holes and insects present (5% Extensive/severe holes and
loss)
10% loss)
insects (> 10% loss)
Deterioration of wood brought about by vehicles or snowplough blades scraping against wood
surfaces, coupled with the abrasive influence of sand, dirt or debris.
< 5% loss
5% - 10% loss
> 10% loss
Physical damage which results from vehicular collision from overloading of a member
< 5% loss
5% - 10% loss
> 10% loss
Fire is evidenced by charring and is usually confined to the wood surface. Chemical damage
may result from the use of non preservative chemicals on the wood surface over a long period of
Fire and Chemical time
Damage
Slight charring or
Deeper charring or softening
Extensive damage with loose
softening with < 5%
with slight loose connectors with
and severely deformed
section loss
5% - 10% section loss
connectors > 10% section loss
Connections are loosened due to repetitive or dynamic loads, wear or decay of members
connected and corrosion of the connectors
Connection
Deficiencies
< 5% loose bolts or
< 10% loose bolts or severe rust > 10% loose bolts or severe
severe rust
rust
2-110
Apr. 2008
Table A.4
MASONRY (Reference: Part 1 Sect. 2.5, Part 2 Table 4.11)
CONDITION STATE
DEFECT
GOOD (LIGHT)
FAIR (MEDIUM)
POOR
Incomplete separation into one or more parts with or without space between
Cracking
< 0.3 mm wide
Splitting
Spalling
Disintegration
Splitting, Spalling
Disintegration
Loss of Mortar or
Stone
0.3 to 1.0 mm wide
> 1.0 mm wide
The opening of seams or cracks in the stone leading to the breaking of the stone into large
fragments
The breaking or chipping away of pieces of the stone from a larger stone
Gradual breakdown of the stone into small fragments, pieces or particles
Hairline cracking and
Narrow cracking or chipping
minor loss of stone
away of stone with section loss 50
surface with section loss <
to 100 mm
50 mm
Extensive spalling and
disintegration of stone with
section loss > 100 mm
Result of the destructive actions of frost, erosion, plant growth or softening by water containing
dissolved sulphates or chlorides.
Mortar lost from joints in Mortar lost from joints over an Extensive mortar/stone loss
a few places to a depth of extended area to a depth of 20 to endangering the stability of the
20 mm
50 mm
structure
2-111
Apr. 2008
Table A.5
ASPHALT WEARING SURFACE (Reference: Part 1 Sect. 2.7, Part 2 Table 4.1)
CONDITION STATE
GOOD (LIGHT)
Bond Defects
Cracks
FAIR (MEDIUM)
POOR
(SEVERE / VERY
SEVERE)
Linear fracture extending partially or completely through the pavement
Pattern (e.g.
Map, alligator,
radial, edge) and
isolated
1—5 mm wide
6—10 mm wide
> 10 mm wide
Loss of bond
Widespread loss of bond and delamination may occur between the asphalt pavement and
deck surface, between the waterproofing and the deck surface, between the waterproofing
and the asphalt pavement or between individual lifts of pavement
< 150 mm in diameter
150 to 300 mm in diameter
> 300 mm in diameter
The formation of transverse undulations in the pavement surface consisting of closely
spaced valleys and crests
Rippling
A few noticeable bumps Several bumps producing a Numerous bumps producing a
rough ride
very rough ride and difficulty
maintaining control of vehicle
Progressive deterioration and loss of the pavement material from surface downward
Surface Defects
Ravelling
Slippery
Surface
Shallow disintegration of Shallow to deep disintegration of
pavement with an open
pavement with small/numerous
texture appearance
potholes, open texture and loose
surface material
May result from flushing or from the polishing of the coarse surface aggregates by the
action of repetitive vehicular traffic
There are no severity descriptions given for slippery surfaces as this is a serious and
potentially hazardous situation resulting in loss of riding comfort and loss of vehicle
control (indicate suspected perform deficiency of slippery surface)
The migration of asphalt upwards to the pavement surface in pavements with too much
asphalt in the mix.
Flushing
Wheel track
Surface rutting
Distortion
Potholes
Local
Underlying
Defects
Noticeable loss of
pavement material
Visible colouring of the Distinctive colouring of the Excessive free asphalt gives the
pavement surface
pavement surface with
pavement surface a “wet look”.
occurring in localized excess asphalt free on the
Visible imprints left from
areas
pavement surface
footprints or vehicular traffic
The formation of longitudinal depressions in the pavement at the locations of the wheel
tracks of vehicles
Rutting < 10 mm deep
Rutting 10 to 20 mm deep
Rutting > 20 mm deep
Bowl-shaped holes in the pavement caused by the penetration of water through the
pavement and subsequent heaving of the pavement due to freezing of the entrapped water
and breaking up of the pavement due to traffic action
< 10 mm deep
10 to 20 mm deep
> 20 mm deep
Local delamination is visible as protrusions or bumps (often circular in shape)
Protrusions
(Delaminations)
< 10 mm in height
10 to 20 mm in height
> 20 mm in height
2-112
Apr. 2008
Table A.6
ASPHALT COVERED CONCRETE DECK (Reference: Part 1 Sect. 2.7, Part 2 Table 4.6)
DEFECT
CONDITION STATE
BOTTOM-UP DEFECTS
GOOD (LIGHT)
Wide
Isolated
Cracks
Transverse,
longitudinal
cracks
FAIR (MEDIUM)
POOR
(SEVERE / VERY
SEVERE)
Longitudinal – parallel to the direction of travel, and generally located at or near the
centre of the wheel track, pavement edge or centre-line of bridge
Transverse – across pavement either fully or partially
> 10 mm wide single
cracks
Potholes
Bowl-shaped holes in the pavement caused by the penetration of water through the
pavement and subsequent heaving of the pavement due to freezing of the entrapped
water and breaking up of the pavement due to traffic action
Local
ALL
Underlying
Defects
Local delamination is visible as protrusions or bumps (often circular in shape)
Protrusions
(Delaminations)
ALL
Pattern
Cracks
Incomplete separation into one or more parts with or without space between
Map, edge,
alligator, radial
ALL
Loss of bond
Bond
Defects
Widespread loss of bond and delamination may occur between the asphalt pavement and
deck surface, between the waterproofing and the deck surface, between the
waterproofing and the asphalt pavement or between individual lifts of pavement
ALL
Rippling
The formation of transverse undulations in the pavement surface consisting of closely
spaced valleys and crests
TOP – DOWN DEFECTS
ALL
Ravelling
Slippery
Surface
Progressive deterioration and loss of the pavement material from the surface downward
ALL
May result from flushing or from the polishing of the coarse surface aggregates by the
action of repetitive vehicular traffic
Surface
Defects
ALL
Flushing
The migration of asphalt upwards to the pavement surface in pavements with too much
asphalt in the mix.
ALL
Surface
Distortion
Light and
Medium
Isolated
Cracks
Wheel track
rutting
The formation of longitudinal depressions in the pavement at the locations of the wheel
tracks of vehicles
ALL
Isolated cracks Linear fracture extending partially or completely through the pavement
and
< 10 mm
Transverse,
longitudinal
cracks
2-113
Apr. 2008
Table A.7
COATING (Reference PART 1, Section 2.3 & Part 2 Table 4.4)
DEFECT
Rust Condition Rating
Coating Related
Defects
Checking or
Crazing
Cracking
Alligatoring
Chemical
Attack
Chalking
Undercutting
Adhesion Related
Defects
Blisters
Intercoat
Delamination
Peeling
Underfilm
Corrosion
Application Related
Defects
Bridging
Edge Defects
Shadows
Overspray
Application Related
Defects
Pinholing
Runs
Sags
Pinpoint
Rusting
CONDITION STATE
GOOD (LIGHT)
FAIR (MEDIUM)
POOR (SEVERE / VERY
SEVERE)
Rust condition rating is a visual rating of the surface appearance and is based on ASTM
D610 sketches and is also shown in Appendix C and OSIM Part 2, Figure 4.1.
Rust Condition Rating 2 Rust Condition Rating 3 Rust Condition Rating 4 or more
Fine system of minute cracks in a checkerboard pattern. Caused by weathering and
exposure during curing
ALL
Linear pattern of crack penetrated through coating. Results from weathering, continuing
polymerization or shrinkage
ALL
Large irregular checks across surface. Caused by non compatible layers of coating and
hardening/shrinkage process
ALL
Coating reacting adversely with air borne chemicals or accidental spills
ALL
Powdery appearance of coating surface. Caused by reaction of coating resins to sunlight and
process of weathering.
ALL
Spreading of corrosion under coating from a break. Caused by poor surface preparation
ALL
Dome shaped projections of coating. Caused by solvent or water trapped within paint film
ALL
One coat separates from another. Caused by contaminated surfaces or excessive curing
between coats
ALL
Separation of coating from steel due to poor adhesion
ALL
Corrosion under the coating with the help of from a break. Caused by poor preparation or
porous coating
ALL
Coating bridges across tight corner or debris forming void. Void can trap moisture and
oxygen
ALL
Coating pulls away from sharp edges and corners. Due to insufficient application of coating at
edge
ALL
Coating is applied too thin in the shadow of a rivet, bolts, or other abrupt change in surface
ALL
Some paint particle outside spray pattern dry prior to full coating. Leads to some absorbed
solvent and a more porous surface
ALL
Air bubbles trapped in coating creating voids. Caused by holding spray gun too close
ALL
Downward movement of paint. Caused by over-thinning or depositing too much paint at one
time
ALL
Similar to runs, the downward movement of ‘curtain’ of paint
ALL
Rusting visible at point locations. Caused by insufficient coating thickness on peaks of blast
cleaned substrate
Rate based on appearance and Rust Condition Rating
2-114
Apr. 2008
2-115
Apr. 2008
Part 3 – Additional Investigations
PART 3 – ADDITIONAL INVESTIGATIONS
Contents
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
Page
Introduction ...........................................................................................................................
Material Condition Surveys ................................................................................................
Underwater Investigations ..................................................................................................
Fatigue Investigations ..........................................................................................................
Seismic Investigations ..........................................................................................................
Strength Evaluations ............................................................................................................
Monitoring of Deformations, Settlements Movements and Cracks .................................
Appraisal Indices ..................................................................................................................
3-1
3-1
3-3
3-3
3-3
3-3
3-4
3-4
3.1 INTRODUCTION
During the course of the inspection, the inspector may feel that more detailed information on the structure is required. The
presence of severe material defects or performance deficiencies may necessitate additional investigations to be done. When
requesting an additional investigation, the inspector should also indicate the time frame for completion of the investigation as
described in Section 7 of Part 2.
In addition, an Owner may undertake special studies to determine if any components of a structure are “functionally
obsolete”. A component is considered to be functionally obsolete if it were originally designed and constructed using a
Standard or Code that has since changed. This type of information is usually recorded in the form of “appraisal indices” as
described in Section 3.8.
3.2 MATERIAL CONDITION SURVEYS
Condition surveys involve the detailed measurement and documentation of areas of defects and deterioration that exist on a
structure. Procedures more precise than visual inspection techniques are usually employed. Examples of these procedures
are: material testing of samples, half-cell surveys, etc. For additional information on condition surveys for concrete
elements, refer to the Structure Rehabilitation Manual. Additional information on detailed assessment of structures affected
by alkali-aggregate reaction can be found in CSA A864-00, Guide to the Evaluation and Management of Concrete Structures
Affected by Alkali-Aggregate Reaction. Material condition surveys for wood, called detailed timber investigations, are
described in Part 4, Section 2 of this Manual. Material condition surveys for steel include crack detection, which is usually
part of a fatigue investigation and described in Section 3.4 and Part 4, Section 1, or a detailed corrosion investigation which
is normally carried out as part of an strength evaluation and described in Section 3.6.
As a general guide, material defects in the proportions listed in Table 1 would trigger a detailed condition survey to be done.
It should be noted that Condition Surveys are also carried out on structures that are programmed for rehabilitation or
sometimes when an evaluation is to be carried out.
3-1
Apr. 2008
Table 1: Material Condition Survey Triggers
Condition Survey Type
Concrete Deck
(Asphalt or Concrete surface)
Description
Involves the testing of various core samples, sawn
samples and the delineation of delaminated areas
and areas of high corrosion potential (using halfcell survey)
Condition Survey Trigger
10% of deck top or soffit
element in “Poor” Condition
State
References
Structure Rehabilitation Manual
Non-destructive Delamination
Survey of Asphalt Covered Decks
Involves the delineation of delaminated areas
using non-destructive testing techniques such as
Ground Penetrating Radar, Impact Echo testing,
etc
Involves the testing of various core samples, etc,
and the delineation of delaminated areas and areas
of high corrosion potential (using half-cell survey)
Involves exposing areas of post-tensioning strands
to determine possible corrosion and extent of duct
grouting.
A detailed investigation of the wood components
using techniques such as probing, drilling, coring,
etc.
A detailed survey of the condition of the coating to
confirm the feasibility of over-coating. The survey
involves testing coating adhesion, dry film
thickness, etc. If deterioration is still in the early
stages (Combined area of Fair and Poor greater
than 25%, and Poor is less than 10% at the visual
inspection stage), “over-coating” of the steel may
be a viable rehabilitation option. This involves
cleaning the surface with a wire brush and “overcoating” the entire surface. If deterioration
exceeds the above thresholds, traditional coating
techniques (sandblasting the surface, priming, etc,)
would probably have to be used.
5% of element in “Poor”
Condition State
Condition State
50% of “Deck End” element in
“Poor” Condition State
Condition State
Part 4 of this manual
25% of combined area in “Fair”
and “Poor” Condition States and
the percentage in Poor is less
than 10%.
Structural Steel Coating Manual
Concrete Substructure
Post-Tensioned Strand Investigation
Wood Substructure or
Superstructure
Structural Steel Coating
3-2
Apr. 2008
Nov. 2003 Revision
3.3 UNDERWATER INVESTIGATIONS
Underwater inspection shall be considered for components under water where the depth or clarity of water
does not permit a satisfactory visual inspection. They are also carried out when there is evidence of scour or
undermining of the structure foundations. For scour prone structures, underwater inspections should normally
be carried out at five year intervals, unless information is available to justify either reducing or increasing this
interval. Underwater inspections should only be carried out by qualified divers familiar with the following
CSA Standard: “Occupational Safety Code for Diving Operations”. Additional information on Underwater
Inspections is contained in Part 5 of this manual.
3.4 FATIGUE INVESTIGATIONS
Some jurisdictions have a specific fatigue inspection program for their fatigue prone bridges. This involves
performing regular close-up inspections of steel components and by employing Non-Destructive Testing
techniques, when necessary (See Part 4 of this manual). The prioritizing of bridges that require a fatigue type
inspection is done by carrying out a study of the steel bridge inventory. It involves reviewing details,
construction techniques, materials, etc. The ranking of bridges can be reflected in a fatigue index as described
in Section 3.8.
Fatigue investigations can also be triggered if fatigue cracks are identified during a biennial inspection.
3.5 SEISMIC INVESTIGATIONS
During the course of a detailed visual inspection, the inspector may observe situations that may place
structures at risk if they are in a high seismic zone. The inspector may notice:
•
•
Rocker bearings that are severely inclined and may be in danger of collapse during a seismic
event
The superstructure may be close to the edge of its bearing seats. The bearing seat lengths may
be inadequate during a seismic event.
If some of these observations are made, the inspector can request that a detailed seismic investigation be done.
The inspector should also review the Seismic Index if a general study has been done as described in Section
3.8.
3.6 STRENGTH EVALUATION – LOAD CARRYING CAPACITY
To determine the load carrying capacity of a structure, a strength evaluation should be performed. It is
extremely difficult to determine a load limit with only visual inspection information. Bridge plans should be
reviewed and a structural analysis should be performed. If bridge plans do not exist, measurements should be
taken, similar bridge plans can be reviewed, assumptions can be made and some calculations should be done.
In addition, for steel structures, it is often necessary to accurately measure the thickness of critical members
and determine the actual section loss as it varies across the element. This information should be used in the
evaluation. For concrete structures, section loss in reinforcing steel should also be measured and accounted
for in the evaluation.
3-3
Oct. 2000
3.7 MONITORING OF DEFORMATIONS, SETTLEMENTS, MOVEMENTS AND CRACKS
During a detailed visual inspection, the inspector may have identified elements that have settled, deflected,
rotated or tilted. If the movement has stabilized, immediate action is probably not required. In order to
determine if movements have stabilized, a monitoring program should be implemented, whereby various
measurements are recorded over a period of time and compared to previous measurements.
The propagation of cracks in various materials can also be monitored over a period of time.
3.8 APPRAISAL INDICES
Often, an owner undertakes special studies to determine if any of the structures in the inventory have
components that are “functionally obsolete”. The studies usually consist of specialized inspections in addition
to a more rigorous review of structural details, design parameters, current Code requirements, etc. If
deficiencies are identified, structures are prioritized using “appraisal indices” and policies are set to address
the components that are functionally obsolete. These appraisal indices should be used together with the
material defects and performance deficiencies in determining the optimum rehabilitation or replacement
option for the structure in question.
Examples of appraisal indices are:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Fatigue
•
Identifies fatigue prone structures and sets priorities for close-up visual
inspection
Seismic
•
Identifies structures with poor seismic details and sets priorities for further
seismic evaluations.
Scour
•
Identifies structures with poor scour details and sets priorities for further scour
investigations/inspections (e.g. Underwater investigations).
Flood
•
Identifies structures that are prone to flooding and sets priorities for further flood
investigations/inspections or monitoring programs.
Geometrics
•
Identifies structures with functionally obsolete details such as lane widths,
vertical clearances, horizontal clearances, etc, by comparing the original design
with current Code requirements.
Barrier
•
Identifies structures with functionally obsolete barriers/railings by comparing the
original design with current Code requirements.
Curb
•
Identifies structures with functionally obsolete curbs/sidewalks by comparing the
original design with current Code requirements.
Load Capacity
•
Ranks structures that have been recently evaluated using current Code
requirements. The index gives an indication of excess or insufficient load
carrying capacity.
3-4
Apr.
Oct.2008
2000
Part 4 – Material Condition Surveys
Part 4 - Material Condition Survey
SECTION 1 - STRUCTURAL STEEL................................4-1-1
SECTION 2 - WOOD............................................4-2-1
4-i
Section 1 - Structural Steel
1.1
Non-Destructive Testing Methods for Detection
of Defects in Steel Components ................ 4-1-1
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.1.6
Liquid Penetrant Testing ................
Magnetic Particle .......................
Ultrasonic Testing ......................
Eddy Current ............................
Radiographic Testing ....................
Comparison of Non-Destructive Methods ...
4-1-1
4-1-3
4-1-11
4-1-14
4-1-15
4-1-18
1.2
References for NDT of Structural Steel ......... 4-1-20
1.1
Non-Destructive Testing Methods for Detection of Defects in
Steel Components
A comprehensive non-destructive testing program of steel bridge components
should be carried out whenever the members are cleaned to bare metal for
any reason. At this time, a thorough visual examination of all exposed
surfaces and connections can be implemented along with an examination of
critical areas and components. This can be performed by the use of nondestructive techniques described herein.
Non-destructive testing is a term used to describe a process which allows
materials and structures to be examined for defects without changing or
destroying their usefulness.
A wide variety of techniques have been
devised among which the most commonly used, in addition to visual
inspection, are:
Liquid penetrant or dye penetrant
Magnetic particle
Ultrasonic Testing
Eddy Current testing
Radiographic
(LP)
(MP)
(UT)
(ET)
(RT)
Of the five methods presented, none can satisfactorily identify all
defects, each has its limitations and the accuracy that can be achieved
with all the equipment under laboratory conditions can seldom be obtained
in the field due to normally unfavourable site conditions.
A large variety of defects can be identified using non-destructive testing
procedures and these are classified in three categories;
-
Primary Inherent Defects
Secondary Fabrication Defects
In-Service Defects
Primary inherent defects in the materials used in the manufacturing of
steel structures (plates, forgings, castings structural shapes, etc.)
conform to the applicable standards. The standards permit minor surface
discontinuities and non-significant internal defects which are smaller
4-1-1
than the minimum allowable size.
These defects, which remain in the
finished product and are smaller than the maximum allowable defect size,
usually have little effect on the strength of the member.
Secondary fabrication defects can be introduced into the material during
fabrication. Processes used to produce the final product may introduce
different defects or discontinuities to the structure. These are usually,
but not always, identified through quality control procedures and are
rectified by the fabricator. However, these defects are sometimes missed
and should always be considered in subsequent inspections.
In-service defects arise from cyclic stresses or excessive loading which
result in metal fatigue. This fatigue leads to the initiation of cracks
which propagate and cause component failure.
General corrosion of a
component results in section loss reducing the ability of the component to
support the design load. Pitting Corrosion combined with cyclic stresses
causes stress corrosion cracking. This results in the reduction of a
components strength and ability to carry design loads.
Defects remaining in the finished structure may, due to their shape,
location and service environment, become stress raisers. These stress
raisers compromise structural integrity.
All of the various non-destructive techniques can be applied in the field
to identify and evaluate defects although some techniques are more
suitable than others.
The following sections describe each of the
procedures, along with advantages and disadvantages in field applications.
4-1-2
1.1.1
Liquid Penetrant Testing.
The liquid penetrant method is commonly used in both shop and field
to reveal defects that are open to the surface. It is simple to
carry out, involves little time, is inexpensive and is easily
interpreted. The process consists of the following:

The surface of the metal is carefully cleaned with a wire
brush or by water blasting to remove all loose scale, rust,
etc. followed by solvent cleaning to remove any surface
contaminants.
Grinding or sanding of the surface may burr
over or otherwise obscure defects.

A liquid penetrant, a brilliantly coloured penetrating oil, is
applied to the cleaned surface and allowed to seep into the
surface defects for thirty minutes or more.

Excess penetrant is then removed and a developer agent is
sprayed onto the surface.

The developer dries to a white chalky coating and remains
unchanged in the absence of any defects.
Where surface
defects do exist, the penetrant is drawn to the surface by
capillary action and stains the developer.
The surface can then be visually examined for cracks or other
surface defects which will be revealed by brightly coloured stains
on the white surface.
The dwell time of the penetrant can be varied to detect cracks of
different widths, the finer the crack the longer the dwell time.
Fluorescent penetrants can be used with ultraviolet light to detect
cracks wider than about 3 microns.
The sequence for liquid
penetrant
application
and
typical
images
are
shown
in
figure 1.1.1a. to figure 1.1.1c
4-1-3
Figure 1.1.1a
Steps required for applying liquid penetrant
4-1-4
Figure 1.1.1b
Metal surface after liquid penetrant application.
Figure 1.1.1c
Surface after developer has been applied. A crack
was detected by the small thin red line (bottom
right of the weld ).
4-1-5
Advantages
•
Highly portable
•
Relatively inexpensive
•
Can be applied to a wide variety of non-porous surfaces
•
Rapid method of inspection
•
Results can be recorded photographically
•
No special equipment required
•
Results are visually apparent
Disadvantages
•
Does not indicate depth of flaw
•
Surface must be accessible
•
Cannot detect any sub-surface defects
•
Test site must be cleaned thoroughly before inspection
•
Post cleaning may be necessary
Standards
CGSB 48-GP-9M
Certification of Non-Design Personnel
CGSB 48-GP-12M
Liquid Penetrant Inspection
ASTM-E-165
Standard Practice for Liquid-Penetrant
Inspection Method.
ASTM-E-1770
Standard Method for Visible-Penetrant
Examinations Using the Solvent Removable
Penetrant
4-1-6
1.1.2
Magnetic Particle
Magnetic Particle Testing is used to detect surface and near
surface defects.
When a ferromagnetic material is subjected to a magnetic field,
magnetic flux lines are generated in specific directions, depending
on the placement of the contact electrodes or magnetic poles. When
a defect within the field lies generally at right angles to the
flux lines, the field will be distorted and some of the magnetic
flux will leak out of the steel at the defect.
Fine magnetic
particles (low retentivity iron powder) distributed over the
surface are attracted by the leakage field and held magnetically to
form an outline of the defect.
The area to be examined is magnetized by two current carrying
copper prods held against the surface of the component, a short
distance apart to produce a circular magnetic field.
As only
defects which are perpendicular to the magnetic flux lines, can be
detected, the prods must be moved about and re-positioned to ensure
that all defects are located regardless of orientation.
Both AC and DC electric current is suitable for magnetizing steel
components.
Surface defects are most readily detected with AC
magnetization. DC magnetization provides greater penetration for
detection of subsurface defects.
Electromagnetic yokes produce suitable magnetic fields and are
highly portable.
Figure 1.1.2a shows units used for producing a magnetic field and
figure 1.1.2b illustrates how the yokes are used in conjunction
with particle application for inspection.
4-1-7
Figure 1.1.2a
Typical units used for generating magnetic fields to
locate any defects. Top: Yoke; Bottom: Prods.
4-1-8
Figure 1.1.2b
Typical application of magnetic particles and
field generator (yoke).
4-1-9
Advantages
•
Portable and inexpensive;
•
Can detect fine and shallow surface cracks;
•
Fast and relatively simple to apply;
•
Few limitations on size and shape of parts or structures;
•
Surface cleanliness and cleaning methods not as important as for
liquid penetrant method.
Disadvantages
•
Surfaces must
indications;
•
Requires removal of surface materials which may interfere with
the ability to magnetize the area. (Generally, the area should
be cleaned of debris and loose materials.
Non-conductive
coatings must be removed where the prods contact the metal.);
•
Only detects surface defects with certainty, does not indicate
depth of cracks and defects.
•
Some sub-surface defects are detectable but indications are
diffused;
•
Direction and strength of the magnetic field is critical, flux
lines should be normal to the plane of a defect;
•
Prod method of magnetization can cause arc burns and possible
cracks;
•
Demagnetization is necessary when magnetic particles may
interfere with working metal surfaces, threads on bolts or
subsequent painting operations;
•
Can only be applied to accessible surfaces;
be
reasonably
smooth
to
avoid
non-relevant
Standards
CGSB 48-GP-8M
CGSB 48-GP-11M
ASTM-E109-80
ASTM E709
Certification of Non-Destructive Testing
Personnel
Manual on Magnetic Particle Inspection
Dry Powder, Magnetic Particle Inspection
Standard Practice for Magnetic Particle
Examination
4-1-10
1.1.3
Ultrasonic Testing
Ultrasonic testing is a method in which high frequency sound waves
are introduced into a material for the detection of surface and
internal defects. They pass through the material and are reflected
at interfaces or boundaries such as flaws such as cracks, slag
inclusions, porosity etc., or the back surface of the material.
The reflected waves returning to the source can be displayed as
pulses or signals on the screen of a cathode ray tube. The pulses
or signals relate to the transit time of the sound. The travel
time of the returning pulses is a measure of the distance to the
interface of the defect.
The ultrasonic method is used to detect cracks and various other
types of planar defects in wrought materials, to examining welds in
fabricated components for cracks, slag inclusions and porosity, and
for measuring residual wall thickness of corroded components.
The ultrasonic system is comprised of a high frequency pulse
generator, transducer, receiving amplifier and CRT screen. These
components allow for detection and location of defects. By various
scanning movements in the area of a defect, orientation, size,
shape and nature can be determined through interpretation of the
reflected pulses displayed on the screen of the instrument.
Ultrasonic systems can detect discontinuities that are larger than
one half of the wave length of the signal. A system operating at
5MHz will detect defects larger than about 0.5mm.
A schematic of ultrasonic testing is shown in figure 1.1.3a and the
application of the instrument in figure 1.1.3b & 1.1.3c.
4-1-11
Figure 1.1.3a
.
Schematic of ultrasonic testing equipment
Figure 1.1.3b
Application of ultrasonic testing equipment.
Component was being inspected for voids and metal
defects.
4-1-12
Figure 1.1.3c
Ultrasonic testing of a bridge pin.
Advantages
• Detects the depth and location of cracks and planar defects;
• Very sensitive and can detect small defects such as inclusions;
• With adjustments in procedure (angle-beam method and contact pulse
reflection) can detect internal defects and fatigue cracks;
•
•
•
•
•
•
Few restrictions on size of work piece;
Ideal for testing wrought materials and welds;
Requires access to one surface of the test piece;
Highly portable;
Equipment is relatively inexpensive;
Can be fully automated for scanning uniform shapes.
Disadvantages
• Rough or uneven surface must be ground smooth.
• Interpretation of results dependent on skill, knowledge and
experience of operator.
• No permanent record of the observations.
(Methods have been
recently developed to digitize the screen image which can then be
computer enhanced and/or printed.)
• High noise levels are produced by coarse grain structures such as
cast iron which reduce test efficiency.
Standards
4-1-13
CGSB 48-GP-7M
CGSB 48-GP-6M
ASTM E164
1.1.4
Personnel
Recommended Practices for Ultrasonic
Examination of Structural Welds
Standard Recommended Practice for
Ultrasonic Contact Examination of
Weldments
Eddy Current
Eddy current testing is a method based on the principles of
electromagnetic induction.
The component or part thereof to be
tested is placed within or adjacent to a coil which is excited by
an alternating current.
As the induced current fluctuates, an eddy current is produced
which flows in a closed loop inside the test material. The flow of
this eddy current is affected by the electrical properties of the
part and the existence of defects distorts the electromagnetic
field within the part.
When defect free material is being tested the eddy current flow
remains uniform. In the presence of a crack or other defect, the
eddy current flow is impeded and changes direction, which in turn
alters the electromagnetic field.
Eddy current instruments are
designed to detect and monitor these changes.
Advantages
•
•
•
Can be used for rapid inspection of planar shapes;
Ideally suited for non-ferrous materials
Contact of coil or probe with surface not necessary
consistent separation must be maintained;
•
•
•
•
•
Thin, uniform coatings do not have to be removed;
Detects very small discontinuities;
The size of the defect can be estimated;
No couplants or post cleaning needed;
Good method for sorting materials, checking heat treatment and
detecting hardness variations.
but
a
Disadvantages
•
•
•
•
•
Not suitable for complex shapes;
Shallow penetration of parts, detects surface and subsurface
defects only;
Needs reference samples for comparison purposes;
Material must be electrically conductive;
Surfaces must be smooth and uniform;
4-1-14
•
Skilled and experienced technicians required to interpret the
indirect test results.
Standards
CGSB 48-GP-13M
CAN/CGSB 48.14-M86
Standard for: Certification of NonDestructive Testing Personnel
Advanced Manual for Eddy Current Test
Method
1.1.5 Radiographic Testing
This method is based on the ability of ionizing radiation in the form of
X-rays or Gamma Rays to penetrate solid materials to produce an image on
film or a fluorescent screen (figure 1.1.5a).
The radiation is mostly absorbed when passing through sound and thick
metal while it will pass more readily through cracks, defects and thinner
material. Any differences in density due to inclusions or gas cavities or
thickness variations in the part being examined cause differences in the
absorption rates of the penetrating radiation. The resulting images on
the film appear in various shades of gray, depending upon the amount of
radiation reaching the film. Since cracks or defects absorb less of the
available radiation they create a darker image than the sound material.
The radiograph shown in figure 1.1.5b illustrates
radiograph of a metal arc weld with slag inclusions.
a
typical
X-ray
Under ideal field conditions, radiographic inspections can be used on most
types of solid materials to reveal defects with depths or thicknesses
greater than about 2% of the thickness of the material being examined.
Cracks with depths of about 1.0mm or more should be detected under normal
conditions when the plane of the crack is parallel to the direction of
radiation.
This method is not well suited for testing in field conditions.
It
should, however, not be eliminated as a test method.
The use of
ultrasonic testing would be a suitable test method in place of
radiographic testing.
4-1-15
Figure 1.1.5a
Schematic of typical radiographic equipment.
Figure 1.1.5b
Radiograph of a double vee groove metal arc weld
in steel. The dark contrasting spots are slag
inclusions. The top image has acceptable slag
inclusion the bottom image was considered severe.
4-1-16
Advantages
•
Well suited for the detection of open cracks and internal
defects particularly in welds (inclusions and porosity);
•
Detects cracks oriented approximately parallel to the axis of
the rays;
•
Permanent record of defects can be produced on film;
•
Image is geometrically correct relative to the size, shape and
location of the defect and area examined;
•
Method and equipment well known and accepted;
•
Gamma ray equipment is more portable while the less portable xray equipment can produce better contrast and definition of
defects.
Disadvantages
•
Equipment is hazardous and subject to rigid government controls.
GAMMA RADIATION CANNOT BE TURNED OFF! Radiation sources must
be heavily shielded;
•
Not able to determine the depth of a defect;
•
Cannot detect defects oriented perpendicular to the axis of the
rays.
Varying degrees of detection capabilities for other
orientations relative to the axis of the rays;
•
Both faces of test area must be accessible;
•
Equipment is bulky and may be difficult to use in areas with
limited space or restricted access;
•
Not well suited to the detection of fine, tight cracks.
•
Testing is expensive, particularly in the field.
Standards
CGSB 48-GP-4M
CGSB 48-GP-5M
Personnel
Manual on Industrial Radiography
4-1-17
1.1.6
Comparison of Non-Destructive Methods
All of the foregoing non-destructive testing techniques can be used to
evaluate defects in bridge structures but some are more readily used than
others. Which method or methods that are to be used will depend entirely
upon the information to be derived.
Liquid penetrants are ideally suited in confirming the presence of a
surface defect such as a crack which has been identified by some surface
anomaly during a visual inspection.
The technique will confirm a
discontinuity on the surface of a component and show its size but with no
indication of the depth.
It is not particularly suited for a
comprehensive testing program of welds and assemblies.
Magnetic particle testing is a simple method for quickly evaluating
extensive welds and surface areas. It too is most suited to detecting
surface discontinuities although some sub-surface defects may also be
detected if they are close to the surface. As with liquid penetrants,
this method will delineate the aerial extent of a defect but will provide
no indication of the depth.
Ultrasonic techniques provide a means to identify and measure both surface
and subsurface discontinuities quickly and economically although specific
procedures are required that are unique to the component under test.
Defects within the material appear as anomalies on the screen and through
interpretation by the testing technician, the size of the defects can be
estimated.
Eddy current testing will provide accurate detection of surface and near
surface defects but requires the surface to be quite smooth; any
irregularities complicates the interpretation of the results. This method
is ideally suited to shop inspection of large planar surfaces but as the
geometry of the component under test becomes more complex the observations
become more difficult to interpret. The success of this technique is
highly dependent upon the experience and expertise of the testing
technician.
Radiography is a major non-destructive testing method which is routinely
applied to the examination of welds and assemblies during fabrication. It
is ideally suited to the detection of voids, inclusions, porosity, open
cracks etc., where both faces of the component are accessible.
A
photographic image of a defect is produced illustrating its extent but not
its depth. The equipment is expensive and requires special precautions to
protect against radiation hazards, as is generally not recommended for use
in the field.
4-1-18
Table 1.1.6 gives a relative comparison of each test method to
assist the user in selecting a suitable method for a particular
application.
Table 1.1.6
Comparison of Non-Destructive Methods
Inspection Method
In-Service
fatigue Cracks
Stress Corrosion
Corrosion Pits
Surface Cracks
General
Surface Cracks
Deep Surface Cracks
Internal Cracks
Internal Voids
Welds
Slag Inclusions and
Porosity
Surface Cracks
Internal Cracks,
Lack of Fusion and
Penetration
Legend:
G-Good
Liquid
Penetrant
Ultrasonic
Magnetic
Particle
Eddy
Current
Radiography
G
G
F
G
G
G
G
G
N
G
N
N
P
F
G
F
G
N
N
P
G
G
f
G
G
N
N
G
G
N
N
N
F
F
G
N
F
N
P
G
G
P
G
G
P
N
G
P
N
G
F-Fair/Marginal
4-1-19
P-Poor
N-Not Suitable
1.2
References for NDT of Structural Steel
American Society for Metals, Metals handbook. Non-destructive
inspection and quality control. ASM, Metals Park, OH 12
American Welding Society, Guide for the non-destructive
inspection of welds. ANSI/AWS B.1.10-86, AWS, Miami, FL.
American Welding Society, Structural welding code steel, ANSI/AWS
D1.1-90, AWS, Miami, FL
ASTM Designation: E94 Standard guide for radiographic testing.
1990 Annual book of ASTM standards, vol. 03.03, ASTM, 1989.
ASTM Designation: E1032 Standard method of radiographic
examination of weldments. 1990 Annual book of ASTM standards,
vol 03.03, ASTM, 1985.
FWHA Ultrasonic testing inspection, Federal Highway
Administration, Washington, DC.
4-1-20
Section 2 - Wood
2.1
Methods of Detection of Defects in Wood Components . 4-2-1
2.2 Methods for Detection of Surface Deterioration ..... 4-2-3
2.2.1
Probing ................................. 4-2-3
2.2.2
Pick Test ............................... 4-2-3
2.2.3
Pilodyn ................................. 4-2-5
2.3 Methods for Detection of Interior Deterioration .... 4-2-6
2.3.1
General ................................. 4-2-6
2.3.2
Sounding ................................ 4-2-6
2.3.3
Moisture Meter .......................... 4-2-7
2.3.4
Drilling and Coring ..................... 4-2-9
2.3.5
Shell Depth Indicator ................... 4-2-12
2.3.6
Sonic Testing ........................... 4-2-14
2.4
Post-Inspection Procedure and Treatment............. 4-2-17
2.5
References for NDT of Wood
2.1
Methods of Detection of Defects in Wood Components
........................ 4-2-18
Wood components develop decay from many causes outlined in Part 1,
Section 2, Material Defects, of this manual. There is potential
for decay which results from the reaction between wood and iron
giving rise to loose connections not adequately covered.
Methods for detecting deterioration in wood described herein are
separated into two groups; namely, those which identify exterior or
surface deterioration, and those which are used to assess
deterioration in the body of the wood.
There is no single tool or method that can accurately determine the
extent and severity of deterioration. Of the methods discussed,
none can satisfactorily identify all defects, and each has its
limitations. Usually, the information derived by using a number of
simple tools (figure 2.1) and methods together can provide a
relatively accurate assessment of the extent of defects and
deterioration in wood.
4-2-1
Figure 2.1
Typical tools used for testing wood condition.
Left to Right: pick, hammer, probe, coring
tool, boring tool and treated wood plugs.
4-2-2
2.2
Methods for Detection of Surface Deterioration
2.2.1
Probing
Probing with a pointed tool, such as a knife, awl or screw driver,
can locate decay near the surface of the wood. Decay is indicated
by excessive softness and lack of resistance to penetration of the
probe.
Although the actual procedure is simple, experience is
required to distinguish decay from water-softened wood which is
otherwise sound. In addition, pressure treated wood may be sound
on the surface but rotted beyond the treated layer.
Advantages
•
Simple and quick procedure.
Disadvantages
•
Some soft species, such as cedar, may be particularly
difficult to assess using this method;
•
Interpretation of results subject to experience of
investigator;
•
May not detect interior decay.
2.2.2
Pick test
In this test, a pointed pick, screwdriver or awl is driven a short
distance into the wood, transverse to the grain, to pry out a
sliver of wood from near the edge of a component. Sound wood has a
fibrous structure and pries out as long splinters, while decayed
wood breaks abruptly and crumbles into small pieces (figure 2.2.2).
4-2-3
Figure 2.2.2
Pick test: The picture on the left hand side
illustrates decayed wood while the one on the
right shows sound wood with no decay
Advantages
•
Simple and quick procedure
Disadvantages
•
A large sliver of wood has to be removed for each test and
leaves local damage to the treated surface. This must be
repaired;
•
May not detect internal decay.
4-2-4
2.2.3
Pilodyn
A pilodyn (figure 2.2.3) is a spring-loaded pin device that drives
a hardened steel pin into the wood. The depth of pin penetration
is used as a measure of the degree of decay.
Figure 2.2.3
Typical Pilodyn used for assessing wood
condition.
Advantages
•
Can provide a relatively accurate calibrated/quantitative
assessment of depth of decay;
•
Simple and easy to use.
Disadvantages
•
Equipment has to be calibrated, and results have to be
corrected for moisture content and wood species;
•
May not detect internal decay
4-2-5
2.3
2.3.1
Methods for Detection of Interior Deterioration
General
Interior deterioration is more difficult to locate because there
may be no visible evidence on the surface of the component.
Several methods that can be useful in identifying probable decay
are described. With each of these, the existence and extent of the
problem should be confirmed and defined with core samples.
2.3.2
Sounding
Sounding is a commonly used method and involves striking the
surface of the component with a hammer, or other similar object,
and assessing the resulting tonal quality. A dull or hollow sound
may indicate the presence of internal voids due to decay
(figure 2.3.2). However, other factors may be present which may
make clear identification difficult.
Figure 2.3.2
Simple use of a hammer to sound a wood timber.
Decay is indicated by a hollow sound.
4-2-6
Advantages
•
Quick and simple to apply;
•
Can readily identify very severe deterioration.
Disadvantages
•
Results are subject to interpretation by inspector;
•
Cannot detect wood in incipient or intermediate stages of
decay
•
Cannot determine the extent of decay. Suspect decay must be
verified by other methods such as boring and coring.
2.3.3
Moisture Meter
A moisture meter measures the electrical resistance of the wood
between two metal pins which are driven into the surface
(figure 2.3.3a). The resistance measured is then correlated to the
moisture content in the wood.
A centre probe between the pins
indicates the depth of penetration of the pins.
The pins are
removable and available in various lengths for determining moisture
contents to depths up to 75mm into the wood. The holes left by the
pins can be repaired by treating with preservative.
A measure of the moisture in wood will provide an indication of
conditions that are conducive for decay.
Moisture contents in
excess of about 30% indicate conditions suitable for decay. If the
measurements are carried out after a severe or prolonged period of
dry weather, then moisture levels of 20 to 25 percent may be cause
for concern.
An alternative instrument to check for moisture is a shigometer.
The shigometer uses a pulsed current to measure changes in
electrical conductivity associated with wood decay. A small hole
is drilled into the wood (figure 2.3.3b) and a probe is inserted
into the hole (figure 2.3.3c). The probe measures zones or regions
of decreased resistance. If the readings drop 50% to 75% to that
of sound wood, the region is drilled and cored to determine the
extent and nature of the decay.
4-2-7
Figure 2.3.3a
Typical resistance-type moisture meter.
Figure 2.3.3b
Drilling of the wood beam in preparation for the
shigometer probe.
4-2-8
Figure 2.3.3c
Application of the shigometer probe.
Advantages
•
Highly portable and easy to use;
•
Can determine areas where decay is suspect or possible.
Disadvantages
•
Does not directly detect decay;
•
Must be calibrated and corrected for temperature conditions;
•
Suspect areas must be evaluated by core sampling.
•
Small holes left by the pins, potential areas for wood decay
2.3.4
Drilling and Coring
Drilling and coring are the most positive means to confirm the presence
of internal voids and decay, and to determine the thickness of the
remaining sound material.
In drilling, a hand drill with a 10mm to 20mm diameter bit is used to
drill a hole into the wood. Zones or pockets of decay and deterioration
are noted by ease of drilling and by examination of wood shavings.
Although power drills may be faster, a hand drill is more suitable,
giving the inspector better control and feel in detecting soft pockets.
Coring with an Increment Borer produces a length of solid core from
the wood which can be directly examined for decay and tested. The
equipment used for coring and extraction of a wood core is shown in
4-2-9
figures 2.3.4a to figure 2.3.4c.
Drilling and coring are generally used to confirm suspect areas of
decay identified by other methods (sounding, moisture meter etc.), and
to determine the extent or limits of decay, in terms of depth and
area. Drilling is often used to establish evidence of decay followed
by coring to define the limits of decay and extraction of samples for
further laboratory analysis. Culturing provides a simple method for
assessing potential risk of decay.
The presence of fungi is
indicative of wood in an early stage of decay and in need of
treatment.
Drill bits and borers must be sharp. Dull tools will break, crush and
splinter the wood making interpretation of samples and results
difficult.
Figure 2.3.4a
Equipment used for boring and coring. The piece
of pressure treated wood is used as a plug to
repair damage done by boring.
4-2-10
Figure 2.3.4b
Simple application of the boring tool.
Figure 2.3.4c
Wood core removed by an increment borer.
4-2-11
Advantages
•
Relatively simple and portable tools involved;
•
Drilling provides a rapid initial assessment of interior
deterioration;
•
Coring produces a sample which can be further analyzed in
detail in the laboratory;
•
The core can be used to determine the depth and extent of
existing preservative treatment and sound wood;
•
The inspection hole is useful for the insertion of a shell
depth indicator, to obtain further data.
Disadvantages
•
Interpretation of shavings and cores subject to experience
of inspector, or must be sent to approved laboratory for
analysis;
•
The surface treatment is interrupted by the inspection hole
which must be treated and plugged.
2.3.5
Shell-Depth Indicator
A shell-depth indicator is a metal bar or rod which is notched or
hooked at one end and inscribed with ruled markings along its
length (figure 2.3.5a).
The hooked end is inserted into the
inspection hole and pulled back along the side of the hole. As it
is removed, the hook will be easily pulled through voids and
decayed areas but will catch on the edges of solid sections
(figure 2.3.5b). The inspector can thus determine the depth and
extent of decay and remaining solid portions as read from the ruler
markings.
4-2-12
Figure 2.3.5a
Schematic of a shell-depth indicator.
Figure 2.3.5b
Use of a shell-depth indicator. Note: The wood
member has been partially sectioned to illustrate
the application of the indicator.
4-2-13
Advantages
•
Highly portable and easy to use;
•
Can determine depth of decay
•
Can be used to estimate residual strength.
Disadvantages
•
Needs to be used in conjunction with drilling or coring;
2.3.6
Sonic Testing
Several methods, including sonic wave velocity, acoustic emission
and stress wave analysis have been used for examining wood. These
methods typically involve the use of devices which emit and pick up
sound waves as they travel over the surface and through the depth
of the wood. The variations in the travel time of the sound waves
are recorded and can be related to the residual strength of the
member. No direct indication of decay is obtained.
The basis for these methods is that the characteristics of a sonic
wave are altered in some fashion as it passes through decayed and
softer areas. With further development, these methods will offer a
significant advancement in the accurate detection of decay and
deterioration.
A typical device used for sonic testing is shown in figure 2.3.6
4-2-14
Figure 2.3.6
Typical sonic testing equipment.
Advantages
•
Can determine the approximate location and area of
deterioration through differential application;
•
Portable
•
Calibrated to give the residual strength of the component.
Disadvantages
•
Still developmental to some extent;
•
Cannot be used in the saturated zone at the water line;
•
Requires special training in the use of the equipment;
•
Core samples must be obtained and analyzed to confirm decay
or deterioration and to determine the cause.
4-2-15
2.3.7 Ultrasonic Testing
Ultrasonic testing of timber is similar to sonic testing in that
the variations in travel time of sound waves is measured and
evaluated to provide an indication of the residual strength of a
member. High frequency sound waves are induced into the wood by
means of a transducer and picked up by another mounted on the
opposite side.
Advantages
•
Can determine the approximate location and area of
deterioration;
•
Can be used to evaluate the saturated zone at the water
line;
•
Portable
Disadvantages
•
Still developmental;
•
Requires special training in the use of the equipment and in
the interpretation of the observations
•
Core samples must be obtained and analyzed to confirm decay
or deterioration and to determine the cause.
4-2-16
2.4
Post-Inspection Procedure and Treatment
Several of the inspection methods and tools described involve the
removal or destruction of a portion of the wood. These locations,
such as at drill and probe holes, will become entry holes for
insects and decay. All the surfaces at these locations must be
thoroughly treated with an approved preservative following the
inspection. Holes should be plugged for their full length with
treated wood plugs or dowels, slightly larger in diameter than the
hole.
Generally, treatment with creosote
sufficient for bridge components.
or
copper
naphthenate
is
Failure to carry out a post inspection treatment can result in
development or acceleration of decay at inspection locations.
A summary of the methods typically used for detection of defects
and deterioration in wood is given in Table 2.4
This table is
provided for the purposes of relative comparison of each method,
and to assist the user in selecting a suitable method for a
particular application.
Table 2.4
Comparison of Methods for Detecting Deterioration
in Wood
Surface
Deterioration
Inspection Method
Internal
Deterioration
Exterior
Shallow
Depth
Voids
Insect
Attack
Decay
Probing
Pick Test
Pilodyn
G
G
G
F
F
G
N
N
N
N
N
N
N
N
N
Sounding
Moisture Meter
Drilling & Coring
Shell Depth Indic.
N
G
N
N
G
G
N
N
F
N
G
G
P
P
F
F
F
P
G
G
Sonic
N
N
F
F
F
Ultrasonic
N
N
F
F
F
Radiation
Legend G - Good
2.5
N
N
G
F - Fair/Marginal P - Poor
F
G
N - Not suitable
References for NDT of Wood
ASCE technical Committee on Wood, Evaluation, maintenance and
upgrading of wood structures, A Guide and Commentary. Prepared
by the Subcommittee on Evaluation , Maintenance and upgrading of
4-2-17
Timber Structures under Technical Committee on Wood, ASCE, 1982.
Core H.A. and Cote W.A. Wood structure identification.
Syracuse University Press, Syracuse, NY, 1979
2nd ed.
JANEY J.R. Guide to investigation of structural failure. Report
prepared for ASCE Research Council on Performance of Structures,
ASCE, 1986.
4-2-18
Part 5 – Underwater Inspections
PART 5 - UNDERWATER INSPECTIONS
CONTENTS
SECTION 1 - INSPECTION OF SUBMERGED COMPONENTS..............5-1-1
SECTION 2 - EQUIPMENT AND TOOLS.............................5-2-1
SECTION 3 - FREQUENCY OF INSPECTION.........................5-3-1
SECTION 4 - INSPECTION PROCEDURES...........................5-4-1
SECTION 5 - LEVELS OF INSPECTION............................5-5-1
SECTION 6 - SCOUR INVESTIGATIONS............................5-6-1
5-i
Section 1 - Inspection of Submerged Components
Contents
1.1
General
1.2
Safety
1.3
Training Safety .................................... 5-1-3
1.4
Non-Destructive Testing of Underwater Structures ... 5-1-3
1.4.1
1.4.2
1.4.3
1.4.4
1.4.5
1.4.6
1.1
........................................... 5-1-1
............................................ 5-1-2
Ultrasonic Testing .....................
Magnetic Particle Inspection ...........
Eddy Current............................
Radiography ............................
Coring .................................
Sounding ...............................
5-1-3
5-1-4
5-1-6
5-1-6
5-1-6
5-1-6
General
A significant number of Ontario bridges are built over waterways with
abutment or pier foundations either partly or totally submerged. These
components cannot be thoroughly evaluated from the water surface and must
be occasionally inspected below to determine their condition and state of
deterioration.
The underwater environment, in fresh water, is generally benign to all
usual construction materials. Conditions beneath the surface of the water
are relatively constant throughout the year and vary insignificantly from
year to year. Material which is continuously submerged remains saturated
and there is little oxygen available to promote deterioration. The pH of
most surface water is close to neutral and temperatures below the surface
o
vary over a narrowo range between a minimum of approximately 0 to a
maximum of about 20 C.
The rate of deterioration of construction materials continuously submerged
in fresh water in general is no greater than in the atmosphere and usually
is much less. This does not apply to portions of the structure in the
wave zone that are frequently exposed to the most severe conditions of
both the water and the atmospheric environment. Conditions encountered
here are conducive to rapid deterioration (in spite of the fact that steps
are normally taken to mitigate deterioration; concrete is air entrained,
steel is painted with protective coatings and timber is pressure treated
with a wood preservative) and this area must be carefully inspected. Any
deterioration occurring below the water surface will be evident at the
water line and this area should be observed during all routine
inspections.
Another critical area for all structures founded in water is at the
interface with the material underlying the foundation.
Here,
deterioration of the construction materials is not a significant
problem compared to the potential for erosion of the stream bed under
and around the foundation.
5-1-1
With respect to the personnel performing an inspection, the underwater
environment is hostile.
It is cold, particularly when one is
submerged for an extended period of time, usually dark and frequently
loaded with sediment to the point where no light penetrates.
A wide variety of methods have been developed for underwater
inspection. Several of these techniques are described ranging from
low water wading, skin diving, and diving with SCUBA or a surface
supported air supply. Each method has particular applications and can
provide reliable information on the condition of the structure. The
use of divers using SCUBA or a surface supply is regulated by the
Department of Labour and the "Diving Regulations", O. Reg. 634/86 of
the Occupational Health and Safety Act are rigidly enforced.
During any underwater investigation, all structural components are
visually inspected, where visibility permits, or examined tactually.
Observed conditions are recorded through notes and taped recordings of
voice communications between the diver and the surface, underwater
photography with a hand held still camera or video or with a remotely
operated robot when conditions demand its use. Remote observations
can also be made using sonar or ground penetrating radar.
1.2
Safety
Working on or near the water in any capacity involves a great degree
of risk and precautions must be taken to ensure the safety of all
personnel. The inspection team should be comprised of no less than
three persons who are always in visual contact and each must wear a
DOT approved personal floatation device. Additional safety procedures
which must be followed are identified in Part 2, Section 1.3 of this
manual.
Inspection work performed by a diver, whether with SCUBA or a
surface air supply, is governed by the "Diving Regulations" under
the Occupational Health and Safety Act which require the team to be
comprised of at least three persons, the diver, a stand-by diver
and a tender.
One of them must be identified as the Dive
Supervisor who must not enter the water while the work is in
progress.
In addition, the Regulations clearly identify the
minimum equipment requirements as well as safety precautions.
Under the Act, the ultimate responsibility for the safety of the
workers lies with the employer so it is incumbent upon the owner
to ensure that those employed for this work are competent and
qualified to carry it out.
1.3
Training and Experience
Visibility beneath the water surface is often restricted and the
entire bridge component may not be visible. The overall condition
must therefore be pieced together from a series of observations of
discrete segments.
A meaningful assessment will depend upon the
inspectors ability to understand what he sees, or feels, and how it
relates to the overall structure and its integrity. The underwater
5-1-2
inspector should be knowledgeable in bridge design and construction
details and should know where to look for specific problems and common
defects.
Alternately, a diver lacking this experience must be in
direct voice contact with a knowledgeable and experienced inspector on
the surface who can direct the investigation and evaluate the
observations during the course of the work.
All underwater investigations should be carried out under the direct
supervision of a Professional Engineer who can certify the
completeness and correctness of the work.
When the inspection is carried out by a diver, all members of the
diving team must be fully trained in the use of all diving equipment
and devices and in the performance of underwater work.
1.4
Non-Destructive Testing of Underwater Structures
Non-destructive testing techniques similar to those used above water
can be applied to quantify any defects identified below the water
surface but in each case the equipment and procedures require
modification. These techniques are listed again with considerations
for underwater use.
1.4.1
Ultrasonic Testing
Ultrasound techniques can be used effectively under water. When
used underwater, the transducers must be enclosed in a waterproof
housing. The method is used extensively to determine the residual
thickness of metal sections when only one surface is exposed or
when quick, accurate measurements are required of any component.
Because the water provides a sound connection of the transducer and
the section being measured, a couplant is not required.
Ultrasonic testing of concrete under ideal conditions is difficult
to successfully carry out.
This is due to the unique cracking
patterns that develop in the material and block the sound waves.
The problems encountered are compounded underwater and although it
can be used, the results are not always reliable.
When this technique is used for wood inspection the equipment must
be calibrated for saturated timber material. Residual strength of
the timber can be determined through the application of empirical
methods and formulas which are dependent upon the wood species.
Relative measurements can be made for a single component by
comparing observations from a questionable area to those from at a
known sound location within the same member. Care and experience
are required to assess the results obtained.
1.4.2
Magnetic Particle Inspection
5-1-3
Magnetic particle testing techniques are also used underwater for
cracks or discontinuities in the surface of components.
The
process is the same as used on the surface except the magnetic
particles are in a water suspension of fluorescent dye
(figure 1.4.2).
The flux leakage at the defect creates an
accumulation of the coloured particles indicating location and
size. This deposit can be measured and photographed to create a
permanent record. The surface still must be cleaned with a wire
brush or a water-jet.
5-1-4
Figure 1.4.2
Underwater Magnetic Particle Inspection.
5-1-5
1.4.3
Eddy Current
Eddy current techniques can be used effectively underwater to
locate defects in or near the surface of conductive components, as
described in Section 4.1. Ultrasonic methods are then required to
quantify the size and extent of noted defects or deficiencies. The
method requires a skilled diver who is also a highly trained
testing technician to use the equipment and interpret the results.
The greatest advantage of this system is that cleaning of the
surface is not as critical as with other methods.
1.4.4
Radiography
Radiography is not readily adapted for underwater use and is not
normally used in this environment.
When conditions require the
degree of detail available through the use of this technique, gamma
radiation is most readily utilized but all water must be evacuated
between the radiating source and the object under test.
1.4.5
Coring
Coring of concrete is partially destructive and consideration must
be given to repair of the cavities produced where cores are
removed.
Cores can be tested in accordance with approved
procedures to verify and correlate data obtained by other means.
They can be obtained underwater with purposely designed drills or
from the surface by drilling vertically downward through the
structure.
1.4.6
Sounding
Tonal qualities of sound produced in timber and concrete,
underwater, by a hammer are different than those produced above.
The difference will be noted when comparing sound wood or concrete
to that harbouring significant decay. Sounding may identify the
presence of decay and can provide a rapid indication of the extent
of significant deterioration.
5-1-6
Section 2 - Equipment and Tools
Contents
2.1
Hand Tools.............................................5-2-1
2.2
Power Tools............................................5-2-2
2.3
Photography............................................5-2-2
2.4
Notes and Observations ................................5-2-3
2.1
Hand Tools
To effectively carry out an underwater inspection, the diver must
have available an assortment of hand tools to facilitate cleaning,
chipping, sounding, measuring etc. Many of those used in a Level 1
Inspection for identification of deterioration and quantifying its
extent are also utilized in a Level 2 Inspection to determine
limits of probable deterioration or deficiencies, and for
quantifying size, location, distribution and severity.
Where
samples of material are required, power tools may be needed for
cutting or coring.
Extensive problems may require two or more
divers in the water at the same time who must be in direct voice
contact with each other
A variety of equipment is required for underwater inspection
purposes and this can include almost all hand tools normally used
during a structural inspection of any structure above water.
Those most commonly employed underwater are illustrated in
figure 2.1.
5-2-1
Figure 2.1 Typical Hand Tools for Underwater Inspection
2.2
Power Tools
Work of any nature underwater is physically demanding and where
excessive effort is needed to achieve results, power tools should
be considered.
These can include high pressure pumps where
extensive cleaning is required, and pneumatic and hydraulic power
tools such as saws and drills.
The latter must be purposely
designed to avoid environmental contamination.
2.3
Photography
In all instances where deterioration or defects are identified they
should be recorded photographically if at all possible. The diving
inspector should be equipped with an underwater camera or a land
camera in a water-tight housing.
To record small details like
cracks in structural members or pits due to corrosion, a close-up
lens is required.
A "clear-water" prism is to be used where
visibility is reduced due to sediment or suspended solids.
Underwater video systems provide another means for recording
observations. These must be produced with a real time commentary
5-2-2
by the diver describing what is being recorded. In addition, a
referencing system must be used to graphically identify the
location on the structure of what is being viewed on the screen.
Remotely operated vehicles equipped with a video camera provide a
means for the inspector to visually inspect the submerged portions
of a structure without putting a diver in the water. The equipment
must be used with some form of grid system to monitor the location.
All observations must be interpreted immediately by the inspector
and recorded on the tape as it is produced.
2.4
Notes and Observations
The most practical means for recording observations made underwater
by a diver is to record voice communications during the inspection
on tape. In addition, the diver should be equipped with some means
to produce sketches, while submerged, that will illustrate the
observations.
5-2-3
Section 3 - Frequency of Inspection
Contents
3.1
Routine Inspections....................................5-3-1
3.2
Non-Routine Inspections................................5-3-2
3.1
Routine Inspections
The inspection of the critical area at the water line is a part of
the Routine Visual Detailed Inspections which will identify the
need for a more thorough underwater inspection of the submerged
portions of the structure.
Conditions at each structure vary considerably and the requirement
for
regularly
scheduled
underwater
inspections
cannot
be
generalized. All structures with submerged components should be
inspected below the water surface at least once. This should be
undertaken as soon after original construction as possible to
facilitate early remedial action to rectify any construction
defects or deficiencies.
The need for additional underwater inspections will be identified
at the time of the initial inspection if potential problems are
identified, or through the routine bridge inspection program.
Whenever an underwater inspection is warranted the minimum level of
effort should be a Level 1 Visual Inspection due to the relatively
high cost of mobilizing a dive team to the bridge site. Such an
inspection of the entire structure can be carried out relatively
quickly in the presence of minimum deficiencies and will ensure
that any defects are identified and documented.
Concrete structures will experience little in the way of
deterioration below the critical zone at the water line. Once the
structural element in this region has been determined adequate it
need not be inspected again until other major rehabilitation is
required. Such structures on bedrock foundations may never need
another underwater inspection.
Structures on soil foundations will require regularly scheduled
underwater inspections to evaluate the stability of the stream bed
adjacent to structural components and as part of this assessment a
Level 1 Inspection of the structure can be incorporated.
The
timing of these inspections will be dependent upon the foundation
material and its susceptibility to erosion. For structures in good
repair, in a non-aggressive environment and on stable foundations
5-3-1
these inspections can be scheduled at 10 year intervals. Where the
stream bed is more prone to erosion the interval should be reduced
to 5 years. Where stream bed erosion is a significant problem some
other means should be devised to monitor it.
Zebra mussel infestations are creating unusual problems for
structures where they are established. As they grow and multiply
an anaerobic environment is created at the surface of the substrate
which is conducive to the development of sulphur compounds. These
result in microbial induced corrosion of steel components which can
be considerably more aggressive than normal oxidation. The impact
of the resulting sulphates on a concrete substrate is known to
exist but is yet to be evaluated.
Where these creatures are
established, particularly on steel components, monitoring on a
yearly basis will be required in order to quantify the resulting
deterioration. Their complete removal should be attempted only if
all exposed surfaces are to be given a protective coating to
isolate them from further infestation and to inhibit galvanic
corrosion.
3.2
Non-Routine Inspections
Non-routine underwater inspections will be required as a result of
an unusual event such as after impact by a vessel, exceptional ice
conditions or accumulations of debris or where there is evidence of
foundation movement. At locations with scour prone stream beds, an
underwater inspection should be carried out after any exceptional
flood event.
This will normally be a Level 1 Inspection and will
identify the need for a more thorough assessment.
5-3-2
Section 4 - Inspection Procedures
Contents
4.1
Existing Data..........................................5-4-1
4.2
Wading.................................................5-4-1
4.3
Skin Diving............................................5-4-3
4.4
Deep Diving............................................5-4-3
4.1
Existing Data
Before an underwater inspection is carried out, the Inspector
should review the as-built or construction drawings of the
structure, details of any restoration or rehabilitation work
carried out on the submerged portions and all previous inspection
reports in order to monitor the progress of known defects or
deterioration.
4.2
Wading
Where the water depth is relatively shallow (less than about a
metre), the river bottom is reasonably hard and there is little or
no current, the submerged components can be inspected during the
regular routine inspections with the inspector wearing chest waders
and a personal floatation device.
The critical area for
observations is at and immediately below the water line, and this
can be readily inspected while wading. In clear water, observation
below the surface can be made with the use of a simple viewing tube
as illustrated in Figure 4.2 or with a conventional face mask.
Where visibility below the surface is limited, the critical area
can be examined tactually.
During a wading inspection, the
condition of the stream bed adjacent to the structure can also be
evaluated.
5-4-1
Figure 4.2
Underwater Viewing Tube
5-4-2
4.3
Skin Diving
An underwater visual inspection in shallow, clear water may be
carried out from the surface by an inspector who is competent and
comfortable when skin diving with a face mask, swim fins and a
snorkel. The critical area at the surface will be clearly visible
as should the stream bed at the base of the foundation.
Although skin diving is not regulated by the Ministry of Labour, it
must be carried out in a manner that will not jeopardise the safety
of the diver.
The skin diver must be tethered to a float on the
surface or to another member of the inspection team on shore or in
a boat.
4.4
Deep Diving
Where the depth is more than about a metre, particularly where
there is limited visibility, most underwater inspections will be
carried out by a diver equipped with SCUBA or a surface air supply.
With this equipment there are few limitations. The diver can work
at any depth encountered at bridges in Ontario and under all
conditions of flow and visibility.
Underwater inspections can be carried out most readily using SCUBA
due to its convenience and mobility but under some circumstances a
surface air supply will be essential for a thorough examination of
the submerged portions of a structure.
The type of equipment
needed for the specific site must be identified through a Site
Reconnaissance Survey by the Diving Supervisor before commencing
the inspection to determine water depths, flow conditions, unusual
potential hazards, underwater visibility, special tool or
inspection procedure requirements, etc.
5-4-3
Section 5 - Levels of Inspection
Contents
5.1
Levels of Inspection.................................. 5-5-1
5.2
Level 1 - Visual Inspection .......................... 5-5-2
5.3
Level 2 - Detailed Inspection ........................ 5-5-3
5.3.1
5.3.2
5.3.3
5.3.4
5.1
Detailed Inspection of Steel Structures.....
Detailed Inspection of Concrete
Structures..................................
Masonry.....................................
Wood........................................
5-5-3
5-5-5
5-5-5
5-5-5
Levels of Inspection
With all structures in the fresh water of Ontario, deterioration of
underwater components is generally going to occur at and just below the
water surface and at the interface with the soil.
The most severe
deterioration of all materials will be in the wave zone where they are
exposed to the deleterious affects of both the water and the atmospheric
environment. Erosion of the stream bed and undermining of the structure
is the greatest concern at the bottom. Between these two locations,
little if any significant problems due to deterioration will develop
except possibly in acidic streams. This may result in deterioration of
all submerged components and dictate the need to assess all exposed
surfaces.
One exception is masonry structures which can experience the softening
and loss of mortar from all the joints in the exposed surfaces.
Another is structures infested with zebra mussels. These animals are
found in the continuously submerged zone below that affected by seasonal
conditions such as exposure, wave action and abrasion from ice and
debris.
When an underwater inspection is to be performed the initial approach
will be a visual inspection using simple, non-destructive testing
techniques.
This should identify and describe any deficiencies in
sufficient detail for a structural evaluation of the problem and form
the basis for any further detailed inspection. The level of detail
required will dictate the procedures and equipment to be used.
5-5-1
5.2
Level 1 - Visual Inspection
A Level 1 Inspection will provide a visual or tactile examination of the
exposed underwater surfaces of a structure in sufficient detail to
detect major damage or deterioration and to confirm the continuity of
all structural elements. It will provide a general assessment of the
condition of the submerged components and will identify the need for a
more detailed inspection.
At the surface, abrasion resulting from floating ice and debris will
usually provide a clean surface for observations. Below the wave zone,
representative areas at known locations for potential problems such as
welds, pile interlocks, connections and connectors may require cleaning
with a scraper and a wire brush to remove algae or other aquatic growths
in order to expose the substrate.
Concrete and timber structures can be sounded with a hammer to provide a
qualitative assessment of the materials beneath the surface. In the
wave zone, timbers are to be carefully probed for indications of
internal decay.
The interface between the structure and the stream bed will be examined
for indications of active or incipient erosion. Where there is active
erosion, characteristic depressions will be observed at the upstream
face of the bridge piers and abutments. Where the stream bed is in a
state of dynamic stability, material being brought into the site over a
period of time is essentially equal to that being carried away, probing
of the bottom with a steel rod to evaluate the relative density of the
stream bed material may indicate the depth of active scour under flood
flow conditions. Any observed signs of erosion are to be noted and
measured.
Structural deficiencies will be apparent in the exposed portions of the
structure. The extent of any such defects should be traced below the
water surface.
Any observed defects or deficiencies are to be noted as to size and
location.
Significant structural defects are to be measured and
photographed in sufficient detail to facilitate a preliminary structural
assessment to evaluate their impact on the safety and integrity of the
structure.
This assessment will confirm the need for a Level 2
Inspection.
Where excessive corrosion is found or suspected, macro photos of the
cleaned surface are required for evaluation and future comparisons.
5-5-2
5.3
Level 2 - Detailed Inspection
A Level 2 Inspection is a highly detailed inspection of critical
structural elements where extensive repairs or possible replacement is
anticipated.
It will be carried out in response to the structural
evaluation of deficiencies identified by a Level 1 Inspection or to
investigate obvious underwater deterioration or defects manifested in
the structure above the surface. This will usually entail extensive
cleaning of the structural elements to remove all algae and bio-fouling,
obtaining
detailed
measurements
and
photographs
and
possibly
non-destructive testing of apparent defects or of critical components.
Sampling of materials for analysis and testing may also be required.
These procedures will be at identified defective areas or at locations
which are representative of the critical submerged portions of the
structure. The specific procedures to be used will be dependent upon
the type of material and its position in the structure.
5.3.1 Detailed Inspection of Steel Structures
The detailed inspection of steel structures will be directed primarily
toward the joints and fasteners with particular attention being given to
welds and the adjacent heat affected zones and known stress raisers.
Cleaning of the components will be carried out with a wire brush or a
water-jet to expose bare metal for a careful and thorough visual
examination. Where defects are identified or suspected the area can be
further examined using non-destructive evaluation techniques such as
ultrasound, magnetic particle or eddy current as described in Section
4.1 of this manual and below.
The extent of corrosion will be noted and where it appears to be
excessive, the residual thickness of the material should be measured.
Mechanical fasteners will be examined for corrosion and tested for
tightness.
Where the structure is comprised of standard rolled sections
measurements of representative elements can be obtained using
conventional measuring devices once the exposed surfaces have been
cleaned.
Flanges of "H" piles can be measured using an outside
calliper, vernier calliper or a micrometer. Where it is necessary to
determine the web thickness a modified calliper as illustrated in figure
5.3.1a may be used in conjunction with a vernier calliper.
Members with only one exposed surface such as pipe piles or sheet piles
can be measured using ultrasound. Discreet pits in the surface of the
component should be measured for depth using a pit gauge, figure 5.3.1b.
The density of the pitting should be recorded photographically.
5-5-3
Figure 5.3.1a
Modified calliper for thickness measurements.
Figure 5.3.1b
Pit Gauge.
5-5-4
5.3.2
Detailed Inspection of Concrete Structures
Deterioration of concrete due to exposure in fresh water is
normally insignificant and a detailed inspection will be primarily
to define construction defects or physical damage.
This will
entail a very careful visual examination with photographs of
observed problems and some non-destructive evaluation techniques to
define the area of concern.
Several of the standard nondestructive and destructive testing procedures and equipment used
to collect data on concrete components above water can be modified
for use underwater.
Where general deterioration of the concrete surfaces is occurring
due to high or low pH of the water, the condition will be apparent
near the surface where specific tests can be carried out.
5.3.3
Masonry
The joint pattern in masonry structures materially limits the use
of non-destructive testing procedures. A qualitative assessment of
the mortar joints can be made using a chisel or screw driver and
the masonry components can be sounded with a hammer.
To quantify any observations requires core drilling vertically
downward because of the extreme care required to recover even the
best mortar in the joints.
5.3.4
Wood
The standard non-destructive and destructive testing procedures and
equipment used to collect data on wood components above water, as
detailed in Section 4.2 can be used directly or modified for use
underwater.
5-5-5
Section 6 - Scour Investigations
Contents
6.1
Scour Investigations...................................5-6-1
6.2
Inspection Procedures for Scour........................5-6-2
6.2.1
6.2.2
6.2.3
6.2.4
6.2.5
Probing......................................5-6-2
Diver Inspections............................5-6-2
Sounding.....................................5-6-3
Sub-Bottom Profiler..........................5-6-3
Ground Penetrating Radar.....................5-6-4
6.3
Corrective Actions.....................................5-6-4
6.1
Scour Investigations
Bridge components in or adjacent to streams need to be investigated
to determine if the bridge is scour critical. A scour critical
bridge is one with abutment or pier foundations which are unstable
due to scouring of the stream bed or which potentially may become
unstable due to scour.
This assessment will be based on a
geotechnical evaluation of the site, the hydrology of the tributary
drainage basin with respect to observed floods and potential floods
and the hydraulics of the watercourse considering the reaches
upstream and downstream of the structure as well as the water
passages through it.
Each bridge should be rated on its propensity for damage due to
scour based on:
* Hydraulic capacity relative to the flood potential of the
tributary basin;
* Water velocity through the structure under "bank full"
condition and the design flood;
* Erodibility of the stream bed;
* Stability of the watercourse, does it have a tendency to
meander;
5-6-1
Based on soil types and the water velocity through the bridge opening
the following scour potential ratings should be applied.
Stream bed
Material
Bank Full
Velocity
Rating
Granular
and Silt
<1 m/s
1-2 m/s
>2 m/s
5
3-4
2
Clay/Till
<2 m/s
2-3 m/s
>3 m/s
5
4
3
Shale
Limestone
Granite
> 3m/s
>5 m/s
4
4
6
A rating of 6 indicates scour will never be a significant problem
whereas a rating of 3 or less indicates the need for further
investigations and possible protective measures. In addition to the
foregoing scour rating, each structure must be rated based on the
potential for collapse or severe damage as a result of scour and its
impact on the travelling public.
6.2
6.2.1
Inspection Procedures for Scour
Probing
Where the erosion potential of a bridge site is great (rated 3 or
lower) the stream bed may be in a state of dynamic stability with a
continuous bed load moving through the site. Under these conditions
there can be very significant erosion during a flood but as the flow
diminishes the stream bed is re-established at or close to its
original condition. Where this condition is suspected, the stream bed
must be carefully evaluated by probing or through various geotechnical
techniques that can produce a sub-bottom profile of undisturbed soil.
6.2.2
Diver Inspections
A visual examination of the stream bed by a diver will indicate if
active erosion is occurring and will identify exposed piles or the
underside of spread footings. Where the stream bed is in a state of
dynamic stability and infilling of erosion features has occurred,
probing of the bottom adjacent to abutments and piers may reveal loose
sediments as well as the depth to sound material.
5-6-2
6.2.3
Sounding
The stream bed, both upstream and downstream of the structure and
within the water passages should be sounded where any potential
exists for scour.
Sounding is best obtained by using a recording
type echo sounder with particular attention being given immediately
adjacent to the abutments and piers.
The position of all
observations should be related to the centre line of the bridge.
Where the scour rating is 3 or lower, the stream bed should be resounded after every spring freshet and all other significant flood
events. If the stream bed stabilizes at an elevation that does not
threaten the stability of the structure the soundings can be
scheduled at five year intervals and after any major flood event.
The area of concern should extend approximately 30m upstream and
downstream from the face of the bridge.
A narrow beam transducer (50 or less), operating at a frequency of
200kHz or more will produce a reasonably accurate indication of the
bottom profile.
A wider angle will result in more extraneous
signals due to reflections off the vertical surface and will be
more difficult to interpret.
A scanning type sonar with a rotating head can also be used to
trace down the face of a pier and across the stream bed,
identifying any cavities beneath the foundation.
Sonar equipment is reasonably portable and can generally be mounted
in or on any type of boat. The results are graphically recorded on
a strip chart as a permanent record and these are easily
interpreted. Weed growth on the bottom will affect the accuracy of
observations and air in the water will materially affect the
signal, sometimes obscuring it completely.
6.2.4
Sub-Bottom Profiler
A sub-bottom profile can frequently be obtained using sonar
operating in the range of 50kHz or less.
Such equipment will
obtain reasonable penetration of the loose sediments on the bottom
but with some loss of detail.
The equipment is similar in every respect to conventional sonar
although some expertise is required for interpretation of the data.
5-6-3
6.2.5
Ground Penetrating Radar
Ground penetrating radar is a relatively new procedure for
geotechnical investigations and its applications are being rapidly
expanded. It is well suited to sub-bottom profiling from a boat,
or from surface ice. Its greatest advantage over sonar is that the
signal is not affected by entrained air.
The equipment is considerably more bulky than sonar and
considerable expertise is required for computer enhancement of the
recorded data and for the interpretation of the results.
6.3
Corrective Actions
If the scour investigations and assessment indicate that the
stability of a structure is jeopardised, then appropriate actions
should be taken to mitigate the problem. This will usually be in
the form of armour stone or rip-rap placed on the stream bed in
close proximity to the bridge components.
Any proposed method of control will require a hydraulic analysis of
the watercourse downstream of the structure and through the bridge
openings to determine its impact on the capacity of the water
passages and on the stability of the stream bed beyond the
protection.
5-6-4
5-6-5

Ontario Structure Inspection Manual (OSIM)

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